Reproduce the Error: `n()` must only be used inside dplyr verbs.

Answers

Answer 1

To reproduce the error `n() must only be used inside dplyr verbs`, you can try calling the `n()` function outside of a `dplyr` verb such as `filter()` or `summarise()`. For example, you could try running the following code:

```
# Load necessary packages
library(dplyr)

# create a sample data frame
df <- data. the frame(x = c(1, 2, 3, 4), y = c("a", "b", "c", "d"))

# call n() outside of a dplyr verb
n(pdf)
```

This should produce the error message `Error: n() must only be used inside dplyr verbs.` since `n()` is a `dplyr` function that is meant to be used within `dplyr` verbs like `filter()` and `summarise()`.
It seems like you encountered an error while using the dplyr package in R. The error message you received, "`n()` must only be used inside dplyr verbs," indicates that you are attempting to use the `n()` function outside of a valid dplyr context.

To avoid this error, ensure that you're using the `n()` function within a dplyr verb such as `mutate`, `summarise`, or `filter`. For example, if you want to count the number of rows in a data frame named `data`, you can use the following code:

```R
library(dplyr)
result <- data %>%
 summarise(count = n())
```

By using `n()` within the `summarise` verb, you'll correctly reproduce the row count and avoid the error.

Learn more about dplyr here:

https://brainly.com/question/30982556

#SPJ11


Related Questions

All of the following statements about rear drum parking brakes are true EXCEPT: the lever forces the wheel cylinder pistons out to force the brake shoes against the drum.

Answers

All of the following statements about rear drum parking brakes are true except the lever forces the wheel cylinder pistons out to force the brake shoes against the drum.

The lever does not force the wheel cylinder pistons out to force the brake shoes against the drum. Instead, the lever directly pushes the brake shoes against the drum, bypassing the wheel cylinder pistons. This action provides the necessary force to hold the vehicle stationary when the parking brake is engaged.

With this system, friction is generated by pressing the brake linings against the inside surfaces of the drums. This friction converts kinetic energy into thermal energy. Drum brakes are on each of your vehicle's axles and contain about 10 different parts, including the axle, slack adjuster, and brake drum itself. While a safety valve is part of the air brake system, it is not part of the drum brake.

A parking brake controls the rear brakes and is a completely separate device from your vehicle's regular hydraulic brakes. It is in charge of keeping a parked vehicle stationary; it will prevent the car from rolling down a hill or moving.

Learn more about brakes: https://brainly.com/question/14937026

#SPJ11

Sketch a control system for a thermostatically controlled electric water heater. Alow water level switch disconnects the heating elements if water is not present inthe heater. Also, the system has a high water temperature safety switch.

Answers

A possible control system for a thermostatically controlled electric water heater would involve the use of multiple switches and sensors to ensure safe and efficient operation.

The system would be designed to turn on the heating elements when the water temperature falls below a certain set point, and to turn them off when the temperature rises above the desired level. This would involve the use of a thermostat that measures the temperature of the water and sends a signal to the heating elements to turn on or off as needed.

To ensure that the heating elements do not overheat the water and cause damage or create a safety hazard, a high water temperature safety switch would be incorporated into the system. This switch would be set to turn off the heating elements if the water temperature exceeds a certain level, providing an additional layer of protection against overheating.

In addition, an allow water level switch would be included to disconnect the heating elements if water is not present in the heater. This switch would help prevent damage to the heating elements and the surrounding components by preventing them from operating when there is no water in the system.

Overall, this control system would provide a reliable and safe way to control a thermostatically controlled electric water heater, ensuring that it operates efficiently and safely at all times.

Learn more about electric  here:

https://brainly.com/question/8971780

#SPJ11

The shear strength of the soil is important to find the bearing capacity of a shallow foundation
True or False

Answers

The statement "The shear strength of the soil is important to find the bearing capacity of a shallow foundation" is true because it directly affects the foundation's ability to withstand loads without experiencing failure.

The bearing capacity of a shallow foundation depends on several factors, including the strength of the soil in which it is placed. The shear strength of the soil is one of the key factors that influences the bearing capacity of the foundation. Shear strength refers to the ability of the soil to resist forces that tend to cause sliding or deformation along a plane parallel to the ground surface.

Higher shear strength means that the soil is better able to support the load of the foundation without excessive settlement or failure. Therefore, it is important to consider the shear strength of the soil when designing and analyzing shallow foundations.

Learn more about the foundation:

https://brainly.com/question/31390928

#SPJ11

3. (25) Two specimens with the same dimensions and material were subjected to fatigue tests. The figure below describes the experimental dynamic stress conditions applied in the fatigue test. Specimen 1 was subjected to test 1 and specimen 2 was subjected to test 2 conditions. 300 - Test 1 - Test 2 Stress (MPa) -100 -200 000 5 10 - 15 20 25 Time A. (15) Calculate the mean stress and stress amplitude applied in tests 1 and 2. B. (5) If the specimen material fatigue behavior does not show fatigue limit, which test specimen will have a shorter fatigue life? Why? C. (5) For a material with fatigue limit at 300 MPa, which test specimen will have a shorter fatigue life? Why?

Answers

The answers for A,B,C are

For A, test 1:Mean Stress is 100 MPa, and Stress Amplitude is 250 MPa, and for test 2:Mean Stress is 50 MPa, and Stress Amplitude is 250 MPa.

For B is specimen 2.

For C is specimen 1.

A.

To calculate the mean stress and stress amplitude applied in tests 1 and 2:

Mean Stress = (Maximum Stress + Minimum Stress) / 2
Stress Amplitude = (Maximum Stress - Minimum Stress) / 2

Test 1:
Mean Stress = (300 + (-100)) / 2 = 200 / 2 = 100 MPa
Stress Amplitude = (300 - (-100)) / 2 = 400 / 2 = 200 MPa

Test 2:
Mean Stress = (300 + (-200)) / 2 = 100 / 2 = 50 MPa
Stress Amplitude = (300 - (-200)) / 2 = 500 / 2 = 250 MPa

B.

If the specimen material fatigue behavior does not show a fatigue limit, the test specimen with a shorter fatigue life will be specimen 2.

This is because specimen 2 has a higher stress amplitude (250 MPa) compared to specimen 1 (200 MPa), leading to more significant fatigue damage in specimen 2.

C.

For a material with a fatigue limit of 300 MPa, the test specimen with a shorter fatigue life will be specimen 1.

This is because the mean stress in specimen 1 (100 MPa) is closer to the fatigue limit of 300 MPa, while the mean stress in specimen 2 (50 MPa) is further away from the fatigue limit.

The higher mean stress in specimen 1 makes it more likely to reach the fatigue limit and experience failure sooner.

Learn more about Fatigue: https://brainly.com/question/12564121

#SPJ11

Main method: Write a main method that asks the user to roll the dice. If the user enters "roll" then the methods below are called. If the user enters "quit", then the program ends. The program continues as long as the user enters "roll".After the user enters roll, the result of the dice roll is shown. rollDice should be called here.The score should be calculated and shown to the user, as shown in the sample output.The score returned by calculateScore should be added to a overall score total in main.Then, the user is again prompted to roll the dice. If the user enters "roll" again, then steps 1 and 3 happen again. If the user enters "quit", then the program ends, as noted above. This process repeats until the user enters "quit". The only way the program should end is if the user enters "quit".rollDice method: Returns an array of integers. The function does not accept any input parameters. Simulate the rolling of 3 dice based on C#'s Random class (page 182 of book). Choose a random number between 1 and 6 for each of the 3 die. The three numbers are returned in the array.calculateScore: Returns the the score as an integer. This method should accept an array of integers as a method parameter. This array of integers is what the rollDice method returned earlier. In addition, you will need to accept another parameter as well to achieve the results below.If the all three integers are different, then add each integer to find the sum. For example, if the roll is 1,2,3 then the sum is 6. The bonus string variable in the main method should be set to "No bonus". If two of the integers are the same, then add 25 bonus points to sum, and then add the result of the roll to the sum. For example, if the roll is 1,1,2, then the sum is: 25 bonus points + 1+1+2 = 29. The bonus string variable in the main method should be set to "You rolled a double!"If three of the integers are the same, then add bonus points to sum, and then add the result of the roll to the sum. For example, if the roll is 6,6,6, then the sum is: 50 bonus points + 6+6+6 = 68. The bonus string variable in the main method should be set to "You rolled a triple!"In any case above, the total (or sum) is returned by the function.OutputDo you want to roll or quit: rollThe dice roll is: 1, 2, 3No bonus.Your total roll is: 6Your total score is: 6Do you want to roll or quit: rollThe dice roll is : 1, 1, 2You rolled a double!Your total roll is: 29Your total score is: 35Do you want to roll or quit: rollThe dice roll is: 6, 6, 6You rolled a triple!Your total roll is: 68Your total score is: 103Do you want to roll or quit: quit

Answers

To achieve the described functionality, you can create a program with the following structure:

1. Implement the `roll dice` method that returns an array of integers with three random numbers between 1 and 6.

2. Create the `calculate score` method that accepts an array of integers from `rollDice` and calculates the score based on the provided conditions (no bonus, double, or triple).

3. In the `main` method, use a loop to repeatedly prompt the user to enter "roll" or "quit." If the user enters "roll," call the `rollDice` method and store the result in a variable. Then, call the `calculate Score` method with the array from `rollDice` and store the returned score in a variable. Update the overall score and display the results to the user. Continue the loop until the user enters "quit."

Learn more about program here:

https://brainly.com/question/3224396

#SPJ11

Assume that methods f and g are defined as follows. publie int f(int x) if (x = 0) return 0; } else return g(x - 1); 3 3 public int g(int x) if (x <= 0) return 0; 1 else 1 return (f (x - 1) + x); 1 } What value is returned as a result of the call f (6)? A 0 B. 3 return g(x - 1); public int g(int x) if (x <= 0) return 0; 3 olae return (f (x - 1) + x); > What value is returned as a result of the call f(6) ?
a. 0 b. 3 с. 6 d. 9 e.12

Answers

Assume that methods f and g are defined as follows. public int f(int x) if (x = 0) return 0; } else return g(x - 1); 3 3 public int g(int x) if (x <= 0) return 0; 1 else 1 return (f (x - 1) + x); 1 }

Based on the provided methods f and g, the value returned as a result of the call f(6) is as follows:
First, let's evaluate f(6):
Since x (6) is not equal to 0, call g(6-1), which is g(5).
Now, let's evaluate g(5):
Since x (5) is greater than 0,  return f(5-1) + x, which is f(4) + 5.
Next, need to evaluate f(4):
Since x (4) is not equal to 0, call g(4-1), which is g(3).
Now, let's evaluate g(3):
Since x (3) is greater than 0,  return f(3-1) + x, which is f(2) + 3.
Next, need to evaluate f(2):
Since x (2) is not equal to 0, call g(2-1), which is g(1).
Now, let's evaluate g(1):
Since x (1) is greater than 0, return f(1-1) + x, which is f(0) + 1.
Finally, evaluate f(0):
Since x (0) is equal to 0, return 0.
So, putting all the calls together: f(6) = g(5) = f(4) + 5 = g(3) + 5 = f(2) + 3 + 5 = g(1) + 3 + 5 = f(0) + 1 + 3 + 5 = 0 + 1 + 3 + 5 = 9.
Therefore, the value returned as a result of the call f(6) is 9 (option D).

option 'D' is correct

Learn more about the value returned at:

https://brainly.com/question/8062296

#SPJ11

Please find the "escape" time to r = 926,000km and the velocity at that distance. Thank you.

Answers

The time to escape to r = 926,000 km is 2.76 hours and the velocity at that distance is 10.090 km/s.

The velocity at infinity (v) is 11.366 km/s, which is higher than the velocity at r = 926,000 km due to the gravitational pull of the Earth.

What is the time required to escape to r?

To solve this problem, we can use the vis-viva equation, which relates the velocity of an object in orbit to its distance from the central body:

v² = GM (2/r - 1/a)

where v is the velocity, G is the gravitational constant, M is the mass of the central body, r is the distance from the center of the central body, and a is the semi-major axis of the orbit.

At the surface of the Earth, the radius is 6,371 km, so we can calculate the semi-major axis of the escape trajectory:

a = (r1 + r2)/2 = (6,371 km + 926,000 km)/2

a = 466,185 km

where r1 is the radius of the Earth and r2 is the distance at which the spacecraft escapes.

We can also calculate the velocity at infinity using the formula:

v = √(v1² + 2GM/r1)

where v1 is the initial velocity at the surface of the Earth.

Substituting the values, we get:

v = √(12.910 km/s)

v = 11.366 km/s

To find the velocity at r = 926,000 km, we can use the vis-viva equation:

v² = GM (2/r - 1/a)

Solving for v, we get:

v = √[GM (2/r - 1/a)]

Substituting the values, we get:

v = √[(6.67×10^-11 Nm²/kg²) (5.97×10^24 kg) (2/926,000 km - 1/466,185 km)]

v = 10.090 km/s

To find the time to escape, we can use the equation:

t = ∫(dr/v)

where t is the time, r is the distance, and v is the velocity.

Integrating from the surface of the Earth to r = 926,000 km, we get:

t = ∫(dr/v) = ∫(dr/√[GM (2/r - 1/a)])

t = [(a/√GM) (π/2 + sin^-1(√(r2/a - 1))) - √(r2/GM)]

Substituting the values, we get:

t = [(466,185 km/√(6.67×10^-11 Nm²/kg² × 5.97×10^24 kg)) (π/2 + sin^-1(√(926,000 km/466,185 km - 1))) - √(926,000 km/(6.67×10^-11 Nm²/kg² × 5.97×10^24 kg))]

t = 165.7 minutes or 2.76 hours

Learn more about the vis-viva equation at: https://brainly.com/question/30205676

#SPJ1

Write a program that finds the sum of the all the elements of the vector v, that are divisible by 3. v = [13 17-15 175-17-92 19 19-14 19 19 -1 12-15-3 17 12 19 6 -19 14 18 7 11 10 -4 6-13]

Answers

Here is how you write a program that finds the sum of all the elements of the vector v, that are divisible by 3.

The step-by-step explanation using Python:


1. Define the vector v:
  `v = [13, 17, -15, 175, -17, -92, 19, 19, -14, 19, 19, -1, 12, -15, -3, 17, 12, 19, 6, -19, 14, 18, 7, 11, 10, -4, 6, -13]`


2. Initialize a variable to store the sum of elements divisible by 3:
  `sum_divisible_by_3 = 0`


3. Iterate through the elements of the vector using a for loop:
  `for num in v:`


4. Check if the current element is divisible by 3 using an if statement:
  `if num % 3 == 0:`


5. If the element is divisible by 3, add it to the sum:
  `sum_divisible_by_3 += num`


6. After the loop, print the sum of elements divisible by 3:
  `print(sum_divisible_by_3)`


Here's the complete program:

```python
v = [13, 17, -15, 175, -17, -92, 19, 19, -14, 19, 19, -1, 12, -15, -3, 17, 12, 19, 6, -19, 14, 18, 7, 11, 10, -4, 6, -13]
sum_divisible_by_3 = 0

for num in v:
   if num % 3 == 0:
       sum_divisible_by_3 += num

print(sum_divisible_by_3)
```
This program will find the sum of all the elements of the vector v that are divisible by 3.

Learn more about Vector: https://brainly.com/question/2094736

#SPJ11

Activity 1: XOR Encryption (25 Points)
XOR as a transformation for encryption is a very weak way to protect data. You probably won't find it under the hood of commercial software. This first exercise is meant to get you thinking about the practice of cryptanalysis using a scenario where it is very feasible to recover the key and plaintext via automatic means.
A lone string in this file has been encrypted via the use of the XOR function with a one-character key. Write some code that will automatically identify the string in question. Provide the string in your answer to this question. Hint: you need to write a routine that is able to score a line of English-language text. Adding up established character frequency statistics for letters and choosing the sequence with the highest score is a valid way to do this.
Now that you've found the string, what is the key and the corresponding line of plaintext? Provide both in your answer to this question.

Answers

Encryption is the process of converting plaintext into an unreadable form to protect it from unauthorized access. Plaintext is the original, unencrypted data.

In the given scenario, the XOR function has been used with a one-character key to encrypt a string. However, XOR encryption is a weak method of data protection and can be easily decrypted.

To automatically identify the encrypted string, a code routine must be written to score a line of English-language text. The routine can add up established character frequency statistics for letters and choose the sequence with the highest score. Once the string has been identified, the key and corresponding line of plaintext can be determined.

Without access to the file or the encrypted string, I cannot provide the specific answers to this activity.

Learn more about Plaintext here:

https://brainly.com/question/30876277

#SPJ11

The left-shift operator can be used to pack four character values into a four-byte unsigned int variable. Write a program that inputs four characters from the keyboard and passes them to function packCharacters. To pack four characters into an unsigned int variable, assign the first character to the unsigned intvariable, shift the unsigned int variable left by 8 bit positions and combine the unsigned variable with the second character using the bitwise inclusive OR operator. Repeat this process for the third and fourth characters. The program should output the characters in their bit format before and after they’re packed into the unsigned int to prove that the characters are in fact packed correctly in the unsigned int variable.
//Program needs to accept character input from keyboard and store in packCharacters
//Output should be the characters in their bit format before and after they are packed in to
//the unsigned int to prove they are packed correctly.
#include
unsigned packCharacters(unsigned c1, char c2);
void display(unsigned val);
int main(void)
{
//Define variables
char a;
char b;
char d;
char e;
unsigned result;
unsigned result1;
unsigned result2;
//Prompt user to enter 4 characters
printf("Enter any four characters:");
//Read 4 characters
scanf("%c%c%c%c",&a, &b, &d, &e);
//display 1st char in bits
printf("Representation of '%c' in bits as an unsigned integer is:\n", a);
display(a);
//2nd char in bits
printf("\nRepresentation of '%c' in bits as an unsigned integer is:\n", b);
display(b);
//3rd char in bits
printf("\nRepresentation of '%c' in bits as an unsigned integer is:\n", d);
display(d);
//4th char in bits
printf("\nRepresentation of '%c' in bits as an unsigned integer is:\n", e);
display(e);
unsigned ch = a;
// Call function "packCharacters()" and display resutls
result = packCharacters(ch, b);
result1 = packCharacters(result, d);
result2 = packCharacters(result1, e);
printf("\nRepresentation of '%c\''%c\''%c\' and '%c\' packed in an unsigned integer is:\n", a, b, d, e);
//call the function
display(result2);
return 0;
}
// function to pack 4 characters in an unsigned integer
unsigned packCharacters(unsigned c1, char c2)
{
unsigned pack = c1;
//shift 8 bits to the left
pack <<= 8;
//using or operator pack c2
pack |= c2;
return pack;
}
void display(unsigned val)
{
//bit counter
unsigned c;
unsigned mask = 1<<31;
printf("%7u = ", val);
//loop through bits
for (c = 1; c <= 32; c++)
{
//shift 1 bit to the left
val & mask ? putchar('1') : putchar('0');
val <<= 1;
if (c % 8 == 0)
{
//print blank space
printf("");
}
}
//print new line character
putchar('\n');
}

Answers

The program provided accepts four character inputs from the keyboard and passes them to the function pack characters.

To pack four characters into an unsigned int variable, the first character is assigned to the unsigned int variable, then the variable is shifted left by 8-bit positions, and the second character is combined with the unsigned variable using the bitwise inclusive OR operator. This process is repeated for the third and fourth characters. The program then outputs the characters in their bit format before and after they’re packed into the unsigned int to prove that the characters are in fact packed correctly in the unsigned int variable. The program accomplishes this by calling the function display, which takes an unsigned integer as input and displays its binary representation.

In summary, the program reads four characters from the keyboard, packs them into an unsigned int using the left-shift and bitwise inclusive OR operators, and then displays the packed unsigned int and the binary representations of the individual characters to prove that they have been packed correctly.

Learn more about keyboard here:

https://brainly.com/question/24921064

#SPJ11

Write ARM assembly code to reverse the bits in a register. Use as few instructions as possible. Assume to register of interest is R3.

Answers

Sure, here's the ARM assembly code to reverse the bits in a register:

MOV R0, #32       ; initialize counter to 32
REV R3, R3        ; reverse the bits in R3
loop:
LSRS R1, R3, #31  ; get the rightmost bit of R3
ORRS R1, R1, R1, LSL #31 ; move it to the leftmost position
LSLS R3, R3, #1   ; shift R3 left by one bit
ORRS R3, R3, R1   ; set the rightmost bit of R3 to the value of R1
SUBS R0, R0, #1   ; decrement counter
BNE loop          ; repeat until all 32 bits have been reversed

This code uses the REV instruction to quickly reverse the bits in the register, and then loops through each bit using shifts, masks, and logical operations to put them back in the reverse order. The counter is used to keep track of how many bits are left to process, and the loop repeats until all 32 bits have been reversed.

Learn more about ARM here:

https://brainly.com/question/24108916

#SPJ11

What is one possible output of the following program? code/ecf/global-forkprob3.c 1 #include "csapp.h" 2 3 4 int main() { int a = 5; 5 6 7 if (Fork() != 0) printf("a=%d\n", --a); 8 9 10 printf("a=%d\n", ++a); exit(0); 11 12 } code/ecf/global-forkprob3.c

Answers

One possible output of the program is "a=5" followed by "a=6".

The program first initializes the variable a to 5, then creates a child process using the Fork() function. Since Fork() returns a non-zero value in the parent process, the conditional statement on line 7 executes and decrements a by 1, resulting in a value of 4 in the child process.

Next, the printf statement on line 10 prints the value of a, which has been incremented by 1 to 6 in the parent process. Finally, the exit() function terminates the program.

Therefore, the output will be "a=5" in the child process and "a=6" in the parent process.

Learn more about the conditional statements:

https://brainly.com/question/24567022

#SPJ11

Write a method that takes any two nodes u and v in a tree? T, and quickly determines if the node u in the tree is a descendant or ancestor of node v. You may spend O(n) time preprocessing the tree, where n is the number of nodes in the tree. Give the running time of your method and justify your running time.

Answers

The overall time complexity of our method is O(n) preprocessing time plus O(1) query time. To determine if node u is a descendant or ancestor of node v in a tree T, we can use a technique called LCA (Lowest Common Ancestor).

First, we preprocess the tree T by computing the parent of each node using any traversal algorithm such as DFS or BFS. This preprocessing takes O(n) time as we visit each node once.

Once the preprocessing is done, we can find the LCA of nodes u and v in O(1) time using the parent information we have computed. We start at node u and keep going up the tree until we reach the root or v. If we reach v, then u is a descendant of v. If we reach the root before reaching v, then u is an ancestor of v. We can do the same starting from v to check if v is a descendant or ancestor of u.

Therefore, the running time of our method is O(n) for preprocessing the tree plus O(1) for each query. The O(1) query time is justified because we only need to visit the parents of nodes u and v, which is at most the height of the tree, which is O(log n) in a balanced tree or O(n) in a skewed tree.

Know more about LCA (Lowest Common Ancestor). here:

https://brainly.com/question/30505590

#SPJ11

two rivers have the same depth and discharge. stream b is half as wide as stream a. which stream has the greater velocity?

Answers

The velocity of a river is directly proportional to its discharge and inversely proportional to its cross-sectional area. Therefore, if two rivers have the same depth and discharge, the one with the smaller cross-sectional area will have a greater velocity.

In this case, Stream B is half as wide as Stream A, which means it has a smaller cross-sectional area. Therefore, Stream B will have a greater velocity than Stream A. To visualize this, imagine two rivers with the same depth and discharge, but one is a mile wide while the other is only half a mile wide. The narrower river will have a much stronger current because the same amount of water is being funneled through a smaller space.
In conclusion, the velocity of a river is determined by both its depth and cross-sectional area. When two rivers have the same depth and discharge, the one with the smaller cross-sectional area will have a greater velocity. In this case, Stream B is half as wide as Stream A, so Stream B will have the greater velocity.

For more such questions on velocity visit:

https://brainly.com/question/20899105

#SPJ11

Show that the sum of true strains in three mutually perpendicular direction is zero (i.e. &x + εy +&z = 0, where &x = In to, y = In F. Ez = In у Z Х h w

Answers

To show that the sum of true strains in three mutually perpendicular directions is zero, we can use the formula:

εx + εy + εz = -ν(εx + εy + εz)

where ν is the Poisson's ratio.

Since the directions are mutually perpendicular, we can assume that the material is isotropic, which means that the Poisson's ratio is constant and equal to 0.5.

Substituting this value in the above formula, we get:

εx + εy + εz = -0.5(εx + εy + εz)

Simplifying, we get:

εx + εy + εz = 0

Therefore, we have shown that the sum of true strains in three mutually perpendicular directions is zero.

Learn more about perpendicular  here:

https://brainly.com/question/18271653

#SPJ11

Let Y = X. (a) Find the cdf of Y b) Find the pdf of Y from the cdf of Y. (c) What is the pdf of Y if fx(x) is an even function of r?

Answers

a) The cdf of Y is the same as the cdf of X.

b) The pdf of Y is the same as the pdf of X.

c) The pdf of Y is also an even function of y.


(a) To find the cumulative distribution function (cdf) of Y, we need to use the definition:
Fy(y) = P(Y ≤ y)
Since Y = X, we can rewrite this as:
Fy(y) = P(X ≤ y)
This is just the cdf of X, which we'll call Fx(x):
Fy(y) = Fx(y)
So the cdf of Y is the same as the cdf of X.

(b) To find the probability density function (pdf) of Y from the cdf of Y, we need to take the derivative of the cdf:
fy(y) = d/dy Fy(y)
But we already know that Fy(y) = Fx(y), so we can just differentiate the cdf of X:
fy(y) = d/dy Fx(y)
This is just the pdf of X, which we'll call fx(x):
fy(y) = fx(y)
So the pdf of Y is the same as the pdf of X.

(c) If fx(x) is an even function of x, then we know that:
fx(-x) = fx(x)
This means that the pdf of X is symmetric about the y-axis. But since Y = X, this also means that the pdf of Y is symmetric about the y-axis:
fy(-y) = fy(y)
So the pdf of Y is also an even function of y.

learn more about "probability density function" at: https://brainly.com/question/30403935

#SPJ11

3. Albumin is being separated from IgG by isocratic chromatography using a 50-cm long column having a voidage fraction of 0.25 and a diameter of 10 mm at a mobile phase flow rate of 10 mL/min. The distribution coefficients for lgG and albumin are 1 and 0.1, respectively. If the albumin peak has a characteristic peak width of 0.52 minutes, predict the selectivity and resolution. When the mobile phase flow rate was increased to 20 mL/min, the HETP was found to increase by 80%. Predict the selectivity and resolution at the higher flow rate, which of the two conditions will lead to better separation? 4. Chromatograms were obtained for two different compounds A and B by injecting pure samples of these substances into a 30-cm long column. In both experiments, the same mobile phase flow rate was used. We would like to separate A and B at the same mobile phase flow rate from a mixture containing the same amounts of these substances as used for obtaining the chromatograms. The mobile phase residence time is 2 minutes and the voidage fraction is 0.3. Calculate the theoretical plate height of the chromatographic column, the selectivity and the resolution. If we collect the column effluent from the start to 7 minutes, calculate the purity of A in the sample and the percent yield. Chromatogram for A Chromatogram for B 12 10 8 3 10 0 2 46 810 12 14 16 18 20 Time (min) Time (min)

Answers

For the given separation of albumin from IgG, with a characteristic peak width of 0.52 minutes, the predicted selectivity is 0.1 and the resolution is 1.8.

At the higher flow rate of 20 mL/min, the predicted selectivity is 0.083 and the resolution is 1.5. The condition with the lower flow rate will lead to better separation.

For the separation of albumin from IgG, we can use the equation Rs= (K2 - 1)/(√(α-1) + K2α-1), where Rs is the resolution, K2 is the distribution coefficient of IgG, and α is the selectivity factor between albumin and IgG.

Given K2=1 and α=0.1, Rs=1.8.

When the mobile phase flow rate is increased to 20 mL/min, the theoretical plate height (HETP) of the column increases by 80%. HETP= L/N, where L is the length of the column and N is the number of theoretical plates.

The selectivity factor at the higher flow rate can be calculated as α'= α*(1+HETP_increase), which gives α'=0.18.

Using the same equation for resolution, with K2=1 and α'=0.18, Rs=1.5.

The condition with the lower flow rate will lead to better separation because it provides higher resolution (Rs=1.8) compared to the higher flow rate (Rs=1.5).

To calculate the theoretical plate height (H) for the separation of compounds A and B, we can use the equation H=L/(N^2), where L is the length of the column and N is the number of theoretical plates.

From the chromatograms, the retention times of A and B are 10 and 14 minutes, respectively. Therefore, the peak width is 4 minutes.

Using the equation H= (tR/W)^2* (1-ɛ)/ɛ, where tR is the retention time, W is the peak width, and ɛ is the voidage fraction, we can calculate H for both compounds.

For compound A, H= 2.78 cm. For compound B, H= 3.71 cm.

The selectivity factor (α) can be calculated as α= k2/k1, where k2 and k1 are the distribution coefficients of compounds B and A, respectively. From the chromatograms, k2/k1= 2.

Using the equation Rs= (k2-k1)/√(ɛ(1-ɛ)), we can calculate the resolution (Rs) for the separation of A and B. Rs= 1.58.

To calculate the purity of compound A in the sample, we can measure the area under the A peak and the total area under both peaks (A and B). From the chromatogram, the area under the A peak is 36 and the total area is 78. Therefore, the purity of A in the sample is 46%.

The percent yield can be calculated as the ratio of the area under the A peak to the total area of the sample, multiplied by 100. Therefore, the percent yield is 46.15%.

For more questions like Rate click the link below:

https://brainly.com/question/23715190

#SPJ11

12–109. The beam has a constant E1I1 and is supported by the fixed wall at B and the rod AC. If the rod has a cross- sectional area A2 and the material has a modulus of elasticity E2, determine the force in the rod.

Answers

If the rod has a cross sectional area A2 and the material has a modulus of elasticity E2, the force in the rod is:

Frod = (Fbeam*A₂*E₂*I1)/(48*E₁*L^2) or Frod = -V_A*(A₂*E₂)/(I1*L^2)

To determine the force in the rod, we need to apply the principles of equilibrium and compatibility of deformations.

First, let's consider the equilibrium of forces acting on the rod AC. The only forces acting on the rod are the vertical reaction at A and the unknown force in the rod. Since the rod is in static equilibrium, the sum of vertical forces must be zero. Therefore, we have:

Frod + V A = 0

where Frod is the force in the rod and V_A is the vertical reaction at A.

Next, let's consider the compatibility of deformations between the beam and the rod. Since they are connected at point A, they must have the same vertical displacement at that point. We can use the equation of the deflection curve for a simply supported beam with a concentrated load at the center to determine the vertical displacement at point A:

δ_A = (Fbeam*L^3)/(48*E₁*I₁)

where δ_A is the vertical displacement at point A, Fbeam is the unknown concentrated load on the beam, L is the span of the beam, and E₁ and I₁ are the modulus of elasticity and cross-sectional area moment of inertia of the beam, respectively.

We can also use the equation for the elongation of an axially loaded member to determine the vertical displacement at point A due to the force in the rod:

δ_A = (Frod*L)/(A₂*E₂)

where Frod is the force in the rod, A₂ is the cross-sectional area of the rod, and E₂ is the modulus of elasticity of the rod.

Equating these two expressions for δ_A, we get:

(Fbeam*L^3)/(48*E₁*I₁) = (Frod*L)/(A₂*E₂)

Solving for Frod, we get:

Frod = (Fbeam*A₂*E₂*I₁)/(48*E₁*L^2)

Substituting this expression for Frod into the equilibrium equation, we get:

(Fbeam*A₂*E₂*I₁)/(48*E₁*L^2) + V_A = 0

Solving for Fbeam, we get:

Fbeam = -(48*E₁*L^2*V_A)/(A₂*E₂*I₁)

Therefore, the force in the rod is:

Frod = (Fbeam*A₂*E₂*I₁)/(48*E₁*L^2)

or

Frod = -V_A*(A₂*E₂)/(I₁*L^2)

Learn more about the modulus of elasticity at https://brainly.com/question/29767033

#SPJ11

what are you trying to discover when you test a cable for continuity?

Answers

Testing a cable for continuity, the main objective is to determine if the cable is conducting electrical current as expected or if there are any interruptions or breaks in the circuit. Continuity testing is a simple yet effective way to ensure that a cable is functioning correctly and can be used for a wide range of applications, including telecommunications, networking, and electronics.

To perform a continuity test, a tester is used to send a small electrical current through the cable and then measures the amount of resistance encountered. A low resistance reading indicates that the cable is conducting the electrical current as expected, while a high resistance reading suggests that there may be an interruption in the circuit. This could be caused by a number of factors, including a broken wire, a loose connection, or a faulty connector.By testing for continuity, technicians can quickly identify any issues with a cable and take appropriate steps to rectify the problem. This can help to prevent downtime and ensure that critical systems remain operational. Continuity testing is an important part of routine maintenance and should be performed regularly to ensure that cables are functioning correctly and reliably.

For such more questions on cables

https://brainly.com/question/13151594

#SPJ11

the specific enthalpy of the mass entering or exiting a control volume accounts for the internal energy transfer accompanying the mass crossing the boundary and the

Answers

It considers both the energy associated with the mass and the energy exchange due to the movement of the mass across the control volume boundary

The specific enthalpy of the mass entering or exiting a control volume accounts for the internal energy transfer accompanying the mass crossing the boundary and reflects the change in the thermodynamic state of the mass due to work and heat interactions.

Enthalpy is a useful property to consider in thermodynamic analysis because it takes into account both internal energy and work done on or by the system. Therefore, the enthalpy change of the mass as it crosses the control volume boundary can provide important information about the thermodynamic behavior of the system.

Learn more about mass here:

https://brainly.com/question/19694949

#SPJ11

10 points) if a filter has unity gain (i.e. 0 db) in its passband, you know that the frequency at which the output has half the amplitude of the input is known as the cutoff frequency. hence, the gain is -3 db at the cutoff frequency. however, if the maximum gain in the passband is not 0 db, the cutoff frequency is the point where the gain is 3 db lower than the maximum gain. when measuring cutoff frequency from a bode plot, if you notice that the maximum gain is 8 db, then what is the gain at the cutoff frequency?

Answers

If the maximum gain in the passband is 8 dB, then the gain at the cutoff frequency is 8 dB - 3 dB = 5 dB.

This is because, as mentioned in the question, the cutoff frequency is the point where the gain is 3 dB lower than the maximum gain. Since the maximum gain is 8 dB, the gain at the cutoff frequency would be 8 dB - 3 dB = 5 dB.

It is important to note that the cutoff frequency is a critical parameter for filters as it determines the range of frequencies that are allowed to pass through the filter. Frequencies below the cutoff frequency are attenuated, while frequencies above the cutoff frequency are passed through with little or no attenuation. The cutoff frequency is also important in designing filters as it helps in determining the filter's bandwidth and transition region.If the maximum gain in the passband is 8 dB, then the gain at the cutoff frequency will be 5 dB. It is important to understand the concept of cutoff frequency as it plays a crucial role in filter design and signal processing.

For such more question on frequency

https://brainly.com/question/254161

#SPJ11

create a trigger named trg_line_total to write the line_total value in the line table every time you add a new line row. (the line_total value is the product of the line_units and line_price values.)

Answers

To create a trigger named trg_line_total that writes the line_total value in the line table every time add a new line row, where line_total is the product of the line_units and line_price values,

Follow these steps:
1. Begin by creating the trigger using the "CREATE TRIGGER" statement.
2. Specify the trigger name "trg_line_total".
3. Use the "AFTER INSERT" event to make sure the trigger fires after a new row is inserted.
4. Specify the target table, which is the "line" table in this case.
5. Define the trigger action, which is to calculate and write the line_total value as the product of line_units and line_price.
Here's the SQL code for this trigger:
```sql
CREATE TRIGGER trg_line_total
AFTER INSERT
ON line
FOR EACH ROW
BEGIN
 UPDATE line
 SET line_total = NEW.line_units * NEW.line_price
 WHERE line.id = NEW.id;
END;
```
This trigger will ensure that every time a new row is added to the "line" table, the line_total value will be calculated and written as the product of the line_units and line_price values.

Learn more about triggers at:

https://brainly.com/question/15566804

#SPJ11

how to get coefficients and power of a polynomial in java input string

Answers

To get the coefficients and powers of a polynomial from a Java input string, you can use regular expressions and string manipulation. First, you will need to extract the individual terms of the polynomial using the "+" and "-" operators as delimiters. Then, for each term, you can extract the coefficient and power using another regular expression.

Here's some sample code that demonstrates this approach:

```java
String input = "3x^2 - 2x + 1";

// Step 1: Split the polynomial into individual terms
String[] terms = input.split("\\s*[\\+\\-]\\s*");

// Step 2: Extract the coefficient and power for each term
for (String term : terms) {
   // Use a regular expression to extract the coefficient and power
   String pattern = "(-?\\d*)\\*?x(?:\\^(\\d+))?"; // matches "ax^b" or "a*x^b" or "-ax^b" or "-a*x^b"
   Matcher matcher = Pattern.compile(pattern).matcher(term);
   if (matcher.matches()) {
       String coefficientStr = matcher.group(1);
       String powerStr = matcher.group(2);
       int coefficient = coefficientStr.isEmpty() ? 1 : Integer.parseInt(coefficientStr);
       int power = powerStr == null ? 1 : Integer.parseInt(powerStr);
       System.out.println("Coefficient: " + coefficient + ", Power: " + power);
   }
}
```

In this example, the input string "3x^2 - 2x + 1" is split into three terms: "3x^2", "-2x", and "1". For each term, we use a regular expression to extract the coefficient and power. The regular expression matches strings that start with an optional minus sign, followed by a sequence of digits (the coefficient), followed by an optional "*" and "x", followed by an optional "^" and sequence of digits (the power). We then convert the coefficient and power strings to integers and print them out.

Note that this code assumes that the input string is well-formed and does not contain any syntax errors. You may need to add additional error checking and validation to handle other cases.

Learn more about polynomial here:

https://brainly.com/question/11536910

#SPJ11

At every iteration, we need to increment the Here, j =: the boundary between the non pivot elements we've already looked at and those we haven't, and within the first group - False - True - We need to increment the i at every iteration. Here, i = the boundary between the elements less than the pivot and those greater than the pivot - none of the answers is correct

Answers

At every iteration of a pivot-based sorting algorithm like QuickSort, we need to increment both the i and j indices to properly partition and sort the elements.

The i index represents the boundary between the elements less than the pivot and those greater than the pivot, while the j index represents the boundary between the non-pivot elements we've already looked at and those we haven't. It is crucial to properly update these indices with each iteration to ensure that all elements are correctly sorted.
At every iteration, we need to increment the i. Here,I represents the boundary between the elements less than the pivot and those greater than the pivot. This process helps in separating and organizing the elements based on their relationship with the pivot value during the iteration.

Learn more about iteration here:

https://brainly.com/question/31197563

#SPJ11

How many ways are there to distribute six indistinguishable objects into four indistinguishable boxes so that each of the boxes contains at least one object?

Answers

There are 10 ways to distribute six indistinguishable objects into four indistinguishable boxes so that each of the boxes contains at least one object.

To solve this problem, we can use the stars and bars method. First, we need to distribute one object to each box, which leaves us with two objects to distribute. We can represent these objects as stars, and the boxes as bars. For example, one possible distribution could be:

* | * | * | *

This means that the first box has one object, the second box has one object, the third box has one object, and the fourth box has three objects.

Using this method, we need to find the number of ways to arrange two stars and three bars. This can be represented by the formula (n+k-1) choose (k-1), where n is the number of objects and k is the number of boxes.

Plugging in the numbers, we get:

(2+4-1) choose (4-1) = 5 choose 3 = 10

Therefore, there are 10 ways to distribute six indistinguishable objects into four indistinguishable boxes so that each of the boxes contains at least one object.

Learn more about indistinguishable here:

https://brainly.com/question/29434580

#SPJ11

Answer True/False
a) Running K-means with different initial seeds is likely to produce different results
b) Initial cluster centers have to be data points?
c) Clustering stops when cluster centers are moved to the mean of clusters
d) k-means can be less sensitive to outliers if standard deviation is used instead of the average
e) k-means can be less sensitive to outliers if median is used instead of the average

Answers

The correct answers to the above questions related to k-means, clusters, and standard deviation are, a) True b) False c) True d) False e) False.

a) Running K-means with different initial seeds is likely to produce different results.

True. Different initial seeds can lead to different cluster assignments and final cluster centers, as the algorithm converges to local optima.

b) Initial cluster centers have to be data points?

False. Initial cluster centers can be randomly selected data points, or they can be generated randomly within the data's range.

c) Clustering stops when cluster centers are moved to the mean of clusters.

True. The K-means algorithm stops when the cluster centers do not change significantly between iterations, which occurs when they are at the mean of their respective clusters.

d) K-means can be less sensitive to outliers if the standard deviation is used instead of the average.

False. Using standard deviation instead of the average would not make k-means less sensitive to outliers. K-means are sensitive to outliers because they can significantly affect the mean.

e) K-means can be less sensitive to outliers if the median is used instead of the average.

True. Using the median instead of the mean can make the k-means algorithm less sensitive to outliers, as the median is less affected by extreme values. However, this would be a modification of the standard k-means algorithm, known as K-medians.

Learn more about Standard deviation:

https://brainly.com/question/475676

#SPJ11

Determine whether the following flow fields are irrotational. u = 2xy; v = - x^2y u = y - x+x^2;v = x+y - 2xy u = x^2t + 2y; v = 2x - yt^2 u = -x^2 - y^2 - xyt; v = x^2 + y^2 + xyt

Answers

Among the given flow fields, only F3 (u = x^2t + 2y; v = 2x - yt^2) is irrotational.

To determine whether the following flow fields are irrotational, we need to compute the curl (∇ x F) of each vector field F = (u, v). If the curl is zero, the flow field is irrotational.

1) F1 = (2xy, -x^2y)
∇ x F1 = (∂v/∂x - ∂u/∂y) = (-2xy - 2x) ≠ 0
So, F1 is not irrotational.

2) F2 = (y - x + x^2, x + y - 2xy)
∇ x F2 = (∂v/∂x - ∂u/∂y) = (-2y - 1) ≠ 0
So, F2 is not irrotational.

3) F3 = (x^2t + 2y, 2x - yt^2)
∇ x F3 = (∂v/∂x - ∂u/∂y) = (2 - 2) = 0
So, F3 is irrotational.

4) F4 = (-x^2 - y^2 - xyt, x^2 + y^2 + xyt)
∇ x F4 = (∂v/∂x - ∂u/∂y) = (2x + xt - yt - 2y) ≠ 0
So, F4 is not irrotational.

Therefore, only the third flow field is irrotational, while the first, second, and fourth are not.

Learn more about irrotational flow at https://brainly.com/question/13258313

#SPJ11

the engineering and science of architecture strives to understand and control the forces of pushing and pulling the structure of the building. these forces are called stresses.

Answers

The answer is: a. True. The engineering and science of architecture strive to understand and control the forces of pushing and pulling the structure of the building. these forces are called stresses.

The engineering and science of architecture indeed focus on understanding and controlling the forces (stresses) that act on a building's structure, such as pushing and pulling forces. This ensures the stability and safety of the building for its occupants.

Architecture is the art and science of designing buildings and other physical structures. The engineering and science of architecture refer to the technical and analytical aspects of the field, which are critical to the successful design and construction of buildings.

Engineering in architecture involves the application of scientific and mathematical principles to the design and construction of buildings.

Learn more about the Science of Architecture: https://brainly.com/question/9760486

#SPJ11

Suppose a list is {2.9.5.4. 8. 1}. After the first pass of bubble sort, the list becomes A 2,9,5,4,8,1 B 2,9,5,4,1,8 C 2,5,4,8,1,9 D 2,1,5,4,8,9

Answers

After the first pass of bubble sort, the list becomes {2, 5, 4, 8, 1, 9}. Therefore, the correct answer is option D. 2, 5, 4, 8, 1, 9.

Let's perform the first pass of bubble sort step by step:
Initial list: {2, 9, 5, 4, 8, 1}

1. Compare 2 and 9. Since 2 < 9, do not swap.
  List: {2, 9, 5, 4, 8, 1}
2. Compare 9 and 5. Since 9 > 5, swap them.
  List: {2, 5, 9, 4, 8, 1}
3. Compare 9 and 4. Since 9 > 4, swap them.
  List: {2, 5, 4, 9, 8, 1}
4. Compare 9 and 8. Since 9 > 8, swap them.
  List: {2, 5, 4, 8, 9, 1}
5. Compare 9 and 1. Since 9 > 1, swap them.
  List: {2, 5, 4, 8, 1, 9}

Learn more about bubble sort: https://brainly.in/question/5699939

#SPJ11

You will be dealing with a more serious risk in this section. You may have noticed a second risk listed in SimpleRisk: Leak of sensitive information stored in cleartext files. The inherent risk value of this risk is high (8). In this section, you will prepare a risk mitigation plan using SimpleRisk. Before using SimpleRisk, you will create a paper-based plan. You will need to create three security controls in your risk mitigation plan: one control that reduces the asset value, one that reduces the vulnerability severity, and one that reduces the threat impact. Your security controls should also include examples of both strategic and tactical controls.

Answers

To create a risk mitigation plan for the "Leak of sensitive information stored in cleartext files" scenario using SimpleRisk. First, let's outline a paper-based plan including three security controls that focus on reducing asset value, vulnerability severity, and threat impact.

1. Reducing Asset Value: Implement Data Classification
Data classification involves organizing information based on its sensitivity and importance to the organization. By identifying the most sensitive data and only storing the necessary information, you can reduce the overall value of the data asset. This is a strategic control, as it involves long-term planning and policy implementation.

2. Reducing Vulnerability Severity: Encrypt Sensitive Data
Encrypting sensitive data ensures that even if unauthorized access occurs, the information is protected and cannot be easily read by unauthorized individuals. This is a tactical control, as it involves implementing a technical solution to address the vulnerability directly. Use strong encryption algorithms, such as AES-256, to encrypt all sensitive data stored in files.

3. Reducing Threat Impact: Implement Strict Access Control Policies
Limiting access to sensitive data only to authorized personnel can reduce the likelihood of unauthorized access, leaks, or data theft. This includes implementing role-based access control (RBAC) and ensuring proper authentication methods, such as multi-factor authentication (MFA). This control includes both strategic and tactical elements, as it involves policy implementation and technical solutions.

Once you have outlined your paper-based risk mitigation plan, you can proceed to input these security controls into SimpleRisk to track and manage your risk mitigation efforts effectively. Remember to monitor and review the controls regularly to ensure their effectiveness in reducing the identified risk.

Learn more about risk mitigation plan:

https://brainly.com/question/30928191

#SPJ11

Other Questions
Find diameter of the pipe. a linear function has an x intercept of -8 and a y intercept of 4. which of these is an equation of the linear function? 2x+y=-12x+2y=02x-y=-20x-2y=-8 sort the following features according to whether they apply to generalized transduction, specialized transduction, or both.This process requires integration of phage DNA into the host chromosome.Resulting phages can be transcduced into new cellsThis process may result from infection by lytic phageSome resultant phages carry only host DNAIndividual phages contain a mixture of phage and host DNACertain host genes are packaged at a high frequencyGenes from transducing phages can recombine with DNA in a new hostAll chromosomal genes have an equal chance of being packaged into a phageThe process requires infection by a bacteriophage culture is defined in the text as: group of answer choices the communication between members of similar location. the collective programming of the mind, which distinguishes the members of one group or category of people from another. the main component of formal institutions. the attitudes and behaviors characteristic of a particular social group or organization. What are the positive effects of appropriate behavior on social media? Select 2 options.damaging someones reputationobtaining information and knowledgegetting revenge on a cyberbullysharing ideas and opinionsbeing available to everyone 24/7 A purchasing committee has rated 3 systems on 2 criteria as follows:Compatibility Ease of UseSystem A 70 60System B 80 30System C 40 90Standardized attribute ratings What is the coefficient of the dichromate ion when the following equation is balanced?Fe2+ + Cr2O72- Fe3+ + Cr3+ (acidic solution)A.1 B.5 C.6 D.2 E.3 what racehorse was featured on the covers of time, newsweek, and sports illustrated all in the same week in 1973? the legal principles governing the relationship of principal and agent and of employer and employee are very much the same. true or false? Please answer the question Do you think that where a person is born and raised has an effect on what they will do with their life? How does who we were guide who we will become? What is the total mass, in grams, of products when 2.20 g of propane is burned in excess oxygen according to the balanced chemical reaction below?C3H8 + 5O2 = 3CO2 + 4H2O Are the equipotential surfaces closer together when the magnitude of E is largest?Equipotential surfaces closer together when the magnitude of E is largest:Equipotential surfaces closer together when the magnitude of E is smallest: the use of nonargumentative, emotive words and phrases to persuade or influence an audience is known as home equity loans are similar to home equity credit lines because they are also not secured with any collateral. group of answer choices true false Select the four traditional fungal phyla. Chytridiomycota ("chytrids"), Zygomycota ("zygomycetes"), Ascomycota ("ascomycetes"), and Basidiomycota ("basidiomycetes") a. if a business can make the job seem fun (by offering inexpensive pizza lunches) or at least safe (by nagging the city government to put police patrols around the factory), what probably happens to the supply of labor? A total of 10000 kg of water per second flows over a waterfall 30 m high.If half of the power this flow represents could be converted into electricity, how many 100-W light bulbs could be supplied? all of the following are adapations for living on land except... a limbs b lungs c skin d two eyes a(n) is a product that requires comparison shopping because it is usually more expensive than a convenience product and is found in fewer stores.