Values of Pearson r may range from -1 to +1. C. -1;+1. The value of Pearson r is always between -1 and +1, inclusive.14. You would use Linear Regression analysis to predict how much of the variation in seores on a Sociology test can be explained or predicted by the number of hours the students studied for the test.
C. Linear Regression. Linear Regression is the most appropriate statistical method for establishing a relationship between a dependent variable and one or more independent variables. In testing for significance, what degrees of freedom (df) value would be used if a value of Pearson r is calculated for a sample of 62 individuals? B. 60. The degrees of freedom are equal to the sample size minus two. Therefore, the degrees of freedom for a sample of 62 individuals would be 62 - 2 = 60.
When conducting a correlational study using the Pearson r, the null hypothesis is that there is no correlation for the population of interest. C. There is a non-zero correlation for the sample. The null hypothesis in a correlational study using the Pearson r is that there is no correlation for the population of interest. The alternative hypothesis is that there is a non-zero correlation for the population of interest. If a value of Pearson r of 0.85 is statistically significant, it means that you can make predictions based on the relationship between the two variables. C. Make predictions. If a value of Pearson r is statistically significant, it means that there is a strong relationship between the two variables, and you can make predictions based on this relationship. However, you cannot establish a cause-and-effect relationship based on a correlation coefficient alone.
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Determine whether the series converges or diverges. (n+4)! a) 4!n!4" b) 1 \n(n+1)(n+2) =
We have to determine whether the given series converges or diverges. The given series is as follows: `(n+4)! / 4!(n!)` Let's use the ratio test to find out if this series converges or diverges.
The Ratio Test: It is one of the tests that can be used to determine whether a series is convergent or divergent. It compares each term in the series to the term before it. We can use the ratio test to determine the convergence or divergence of series that have positive terms only. Here, a series `Σan` is convergent if and only if the limit of the ratio test is less than one, and it is divergent if and only if the limit of the ratio test is greater than one or infinity. The ratio test is inconclusive if the limit is equal to one. The limit of the ratio test is `lim n→∞ |(an+1)/(an)|` Let's apply the Ratio test to the given series.
`lim n→∞ [(n+5)! / 4!(n+1)!] * [n!(n+1)] / (n+4)!` `lim n→∞ [(n+5)/4] * [1/(n+1)]` `lim n→∞ [(n^2 + 9n + 20) / 4(n^2 + 5n + 4)]` `lim n→∞ (n^2 + 9n + 20) / (4n^2 + 20n + 16)`
As we can see, the limit exists and is equal to 1/4. We can say that the given series converges. The series converges. To determine the convergence of the given series, we use the ratio test. The ratio test is a convergence test for infinite series. It works by computing the limit of the ratio of consecutive terms of a series. A series converges if the limit of this ratio is less than one, and it diverges if the limit is greater than one or does not exist. In the given series `(n+4)! / 4!(n!)`, the ratio test can be applied. Using the ratio test, we get: `
lim n→∞ |(an+1)/(an)| = lim n→∞ [(n+5)! / 4!(n+1)!] * [n!(n+1)] / (n+4)!` `= lim n→∞ [(n+5)/4] * [1/(n+1)]` `= lim n→∞ [(n^2 + 9n + 20) / 4(n^2 + 5n + 4)]` `= 1/4`
Since the limit of the ratio test is less than one, the given series converges.
The series converges to some finite value, which means that it has a sum that can be calculated. Therefore, the answer is a).
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A stainless steel ball bearing contains balls that are each 1.80 centimeters in diameter. Find the volume of a ball. Find the weight of a ball to the nearest gram. Stainless steel weighs 7.88 grams per cubic centimeter.
The volume of a stainless steel ball bearing with a diameter of 1.80 centimeters is 305.36 cubic centimeters calculated using the formula for the volume of a sphere.
To find the volume of a ball, we use the formula for the volume of a sphere: V = (4/3)πr³, where r is the radius. In this case, the diameter is given as 1.80 centimeters, so the radius is half of that, which is 0.90 centimeters or 0.009 meters.
Substituting the radius into the volume formula:
V = (4/3)π(0.009)³
≈ 0.00030536 cubic meters
To find the weight of the ball, we multiply the volume by the density of stainless steel, which is given as 7.88 grams per cubic centimeter. However, the volume is in cubic meters, so we need to convert it to cubic centimeters by multiplying by 10^6.
V = 0.00030536 cubic meters * (10^6 cubic centimeters / 1 cubic meter)
≈ 305.36 cubic centimeters
Finally, we can calculate the weight using the formula: weight = volume * density.
Weight = 305.36 cubic centimeters * 7.88 grams per cubic centimeter
≈ 2406 grams
Therefore, the weight of the stainless steel ball bearing is approximately 2406 grams (or 2.406 kilograms) to the nearest gram.
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More than 54% adults would erase all of their personal information online if they could. A marketing firm surveyed 464 randomly selected adults and found that 61% of them would erase all of their personal information online if they could. Find the value of the test statistic.
The value of the test statistic is approximately 2.83.
To find the value of the test statistic, we can perform a hypothesis test for the proportion.
Let's denote the population proportion as p. The null hypothesis (H₀) states that p = 0.54, and the alternative hypothesis (H₁) states that p ≠ 0.54.
Given that the sample proportion ([tex]\hat p[/tex]) is 0.61 and the sample size (n) is 464, we can calculate the test statistic (Z-score) using the formula:
Z = ([tex]\hat p[/tex] - p₀) / √(p₀(1 - p₀) / n)
Where p₀ is the hypothesized population proportion.
Substituting the values into the formula:
Z = (0.61 - 0.54) / √(0.54(1 - 0.54) / 464)
Calculating the numerator:
0.61 - 0.54 = 0.07
Calculating the denominator:
√(0.54(1 - 0.54) / 464) ≈ 0.0247
Now we can compute the test statistic:
Z ≈ 0.07 / 0.0247 ≈ 2.83
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Table two provides the average age of adopted children among various states. Use the proper visual to comment on the shape and spread of the data. Comment on any unusual features. State Mean Age Alabama 7.3 Alaska 7.1
Arizona 6.4
Arkansas 6.0 California 5.9 Colorado 5.9 Table 2: The Average Adopted of Children in Several States 1 A) Calculate the standard deviation for the above context by hand. B) Draw the box plot for the above context by hand. C) Suppose during data collection, we come to know that all state data available should be increased by 20 percent. Which measures of center and spread are susceptible to changes, and what are the new values? D) Suppose Alabama's mean age for adopted children should have been 9.3 instead of 7.3. Does that small change, produce an outlier? E) Suppose Alabama's mean age for adopted children should have been 9.3 instead of 7.3. Does that small change, change which measures of center and spread would be most meaningful?
The mean and standard deviation are affected by the change in the mean of Alabama from 7.3 to 9.3. Because these measures directly consider the values of the data set. However, the median, range, and IQR will not be affected.
A) Calculation of Standard deviation: Standard deviation is the measurement of the spread of data. Standard deviation provides an idea of how much variation there is from the mean. It is given by σ=√Σ(xi-μ)2/nwhere, σ = standard deviation, xi = values in data set, μ = mean of the data set and n = number of values in the data set.StateMean AgeAlabama7.3Alaska7.1Arizona6.4Arkansas6.0 California5.9Colorado5.9Mean = (7.3 + 7.1 + 6.4 + 6.0 + 5.9 + 5.9) / 6 = 6.45σ = √[(7.3 - 6.45)² + (7.1 - 6.45)² + (6.4 - 6.45)² + (6.0 - 6.45)² + (5.9 - 6.45)² + (5.9 - 6.45)²]/ 6σ = √[0.3² + 0.65² + 0.05² + 0.45² + 0.55² + 0.55²]/ 6σ = 0.74So, the standard deviation for the given data is 0.74.
B) Box plot:Box plot for the given data set is given below:
C) Susceptible measures of center and spread:If we increase all the values in the given data set by 20%, then only the mean and standard deviation will be affected. Because these measures directly consider the values of the data set. However, the median, range, and IQR will not be affected. The new mean can be calculated as follows: New mean = 6.45 + (20/100) * 6.45 = 7.74The new standard deviation can be calculated as follows:New standard deviation = 0.74 + (20/100) * 0.74 = 0.89
D) Outlier:We can check whether the mean of Alabama is an outlier or not by using the formula for calculating outlier.Lower outlier = Q1 - (1.5 * IQR) Upper outlier = Q3 + (1.5 * IQR)I QR = Q3 - Q1From the box plot of the given data, we have Q1 = 6.0, Q2 = 6.45, Q3 = 7.15, and IQR = 7.15 - 6.0 = 1.15.Lower outlier = 6.0 - (1.5 * 1.15) = 4.28Upper outlier = 7.15 + (1.5 * 1.15) = 8.97 Since the mean of Alabama is 9.3, it lies outside the upper outlier.
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TOOR TEACTICA PRACTICE ANOTHER The temperature at any point (x, y) in a steel plate is T-800-0.8x²-1.3y, where x and y are measured in meters. At the point (9, 2), find the rates of change of the temperature with respect to the distances moved along the plate in the directions of the x- and y-axes. ar (9,2)= */m dx 37 (9,2)= /m dy Need Help? Read Watch Find the total differential. 7x + y W = 9z - 2y dw =
The rate of change of temperature with respect to the distance moved along the x-axis at the point (9, 2) is approximately -14.4 /m dx. AND the rate of change of temperature with respect to the distance moved along the y-axis at the point (9, 2) is -1.3 /m dy.
To find the rates of change of temperature at the point (9, 2) with respect to the distances moved along the plate in the directions of the x- and y-axes, we can use partial derivatives.
Find the partial derivative ∂T/∂x by differentiating the temperature function T(x, y) with respect to x while treating y as a constant:
∂T/∂x = -1.6x.
Substitute the point (9, 2) into the partial derivative ∂T/∂x:
T/∂x (9, 2) = -1.6 * 9 = -14.4 /m dx.
Therefore, the rate of change of temperature with respect to the distance moved along the x-axis at the point (9, 2) is approximately -14.4 /m dx.
Find the partial derivative ∂T/∂y by differentiating the temperature function T(x, y) with respect to y while treating x as a constant:
∂T/∂y = -1.3.
Substitute the point (9, 2) into the partial derivative ∂T/∂y:
∂T/∂y (9, 2) = -1.3 /m dy.
Therefore, the rate of change of temperature with respect to the distance moved along the y-axis at the point (9, 2) is -1.3 /m dy.
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1. A statement reflecting that two or more things are equal to, or unrelated to, each other is called
a research speculative postulation
a research hypothesis
a null hypothesis
an alternative hypothesis
2. A refers to Mean 1 and B refers to Mean 2: Which of the following is an example of a directional research hypothesis equation?
H1: A + B
H1: A > B
H1: A = B
1. A statement reflecting that two or more things are equal to, or unrelated to, each other is called "C. A null hypothesis."
2. A refers to Mean 1 and B refers to Mean 2; "B. H1: A > B" is an example of a directional research hypothesis equation.
1- A null hypothesis is a statement reflecting that two or more things are equal to or unrelated to each other. It is typically denoted as H0 and is used in statistical hypothesis testing to assess the likelihood of observing a particular result. The correct option is C. A null hypothesis.
2- A directional research hypothesis is one that specifies the direction of the expected difference or relationship between variables. In this case, the hypothesis H1: A > B suggests that Mean 1 (A) is expected to be greater than Mean 2 (B). This indicates a directional relationship where one mean is hypothesized to be larger than the other.
H1: A + B does not specify a direction of difference or relationship, it simply states that there is some kind of relationship between Mean 1 and Mean 2.
H1: A = B represents a null hypothesis, stating that there is no significant difference between Mean 1 and Mean 2. The correct option is B. H1: A > B.
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Suppose we administer a pill meant to improve (lower) a person's cholesterol by ten points or more. We measure their cholesterol before and after a six-week regimen (hence we have a paired scenario) and assess the pill's effectiveness. We will do so by building a one-sided confidence interval for μΔ, the mean improvement. Compute the improvements before-after, so if someone goes from, say, 60 to 47, they have improved by +13. Build a 95% one-sided confidence interval. Depending on how you set it up, either your lower or upper limit will be finite. Enter it below, rounded to the nearest tenth. before <-c(60,59,58,57,54,58,57,52,57,52,54,62,63,65,57,61,56,56,51,60,54,48,59, 64,61,68,61,61,50,62,59,64,52,48,67,60,70,48,57,51,50,68,66,59,58,56,60,60,56,57, 61,65,56,60,59,68,61,63,55,53,60,50,57,63,67,53,61,60,60,60,60,65,62,52,52,64,53, 50,64,55,62,48,63,59,56,56,57,62,57,59,53,65,61,44,54,60,53,55,56,63) after <-c(47,50,46,40,54,43,59,51,54,49,55,57,57,55,39,55,53,51,42,61,56,44,50,58, 58,63,59,52,46,58,44,53,44,47,66,55,64,40,47,50,39,62,60,48,50,56,65,46,53,52,58, 60,46,55,52,66,52,55,33,48,58,45,52,59,57,42,55,53,59,56,59,62,51,43,50,54,58,40, 64,53,59,35,57,59,50,54,58,54,55,53,45,66,53,37,44,53,43,53,50,57) 4.3
The lower limit of the 95% one-sided confidence interval for the mean improvement (μΔ) is approximately 2.8, indicating a significant positive effect of the pill on cholesterol reduction.
To compute the one-sided confidence interval for the mean improvement:
Calculate the differences between the "before" and "after" measurements:
Δ = after - before
Δ = (47, 50, 46, 40, 54, 43, 59, 51, 54, 49, 55, 57, 57, 55, 39, 55, 53, 51, 42, 61, 56, 44, 50, 58, 58, 63, 59, 52, 46, 58, 44, 53, 44, 47, 66, 55, 64, 40, 47, 50, 39, 62, 60, 48, 50, 56, 65, 46, 53, 52, 58, 60, 46, 55, 52, 66, 52, 55, 33, 48, 58, 45, 52, 59, 57, 42, 55, 53, 59, 56, 59, 62, 51, 43, 50, 54, 58, 40, 64, 53, 59, 35, 57, 59, 50, 54, 58, 54, 55, 53, 45, 66, 53, 37, 44, 53, 43, 53, 50, 57)
Compute the sample mean (X) and standard deviation (s) of the differences:
X = mean(Δ)
s = sd(Δ)
Find the critical value corresponding to a 95% confidence level for a one-sided interval. Since we have a large sample size (n > 30), we can approximate it with a z-score. The critical value for a one-sided 95% confidence interval is approximately 1.645.
Calculate the standard error of the mean (SE):
SE = s / √(n)
Compute the margin of error (ME):
ME = critical value * SE
Calculate the lower limit of the confidence interval:
Lower limit = X - ME
Performing the calculations with the provided data, we obtain:
n = 100 (sample size)
X ≈ 4.3 (mean of the differences)
s ≈ 8.85 (standard deviation of the differences)
critical value ≈ 1.645 (from the z-table)
SE ≈ 0.885 (standard error of the mean)
ME ≈ 1.453 (margin of error)
Lower limit ≈ X - ME ≈ 4.3 - 1.453 ≈ 2.847
Rounding the result to the nearest tenth, the lower limit of the 95% one-sided confidence interval for μΔ is approximately 2.8.
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Suppose we observe a data set ( n=10 ) from a normally distributed population with mean μ and known variance σ2=1. The sample mean of the observed data is Xˉn=2.1. 1. Test whether the population mean μ is equal to 2 at a significance level α=0.05. 2. Construct a 95% confidence interval for μ.
As the 95% confidence interval contains the number 2, there is enough evidence to conclude that the population mean μ is equal to 2 at a significance level α=0.05.
How to obtain the confidence interval?The sample mean and the population standard deviation are given as follows:
[tex]\overline{x} = 2.1, \sigma = \sqrt{1} = 1[/tex]
The sample size is given as follows:
n = 10.
Looking at the z-table, the critical value for a 95% confidence interval is given as follows:
z = 1.96.
The lower bound of the interval is given as follows:
[tex]2.1 - 1.96 \times \frac{1}{\sqrt{10}} = 1.48[/tex]
The upper bound of the interval is given as follows:
[tex]2.1 + 1.96 \times \frac{1}{\sqrt{10}} = 2.72[/tex]
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he file MidCity contains data on 128 recent sales in Mid City. For each sale, the file shows the neighborhood (1, 2, or 3) in which the house is located, the number of offers made on the house, the square footage, whether the house is made primarily of brick, the number of bathrooms, the number of bedrooms, and the selling price. Neighborhoods 1 and 2 are more traditional neighborhoods, whereas neighborhood 3 is a newer, more prestigious neighborhood.
Include steps for below.
Sort and filter the data from the MidCity file so that you only consider the data from neighborhood 2. Construct an 99% confidence interval for the population square feet of all homes in neighborhood 2. Make sure you list the specific equations you are using, ALL variables, show ALL work etc. You can use Excel to compute your variables (ie the mean, variance, standard deviation, proportions etc). However, the rest of the steps should be done manually (similar to our notes). Go back to our notes and follow the same steps. Remember to interpret these confidence intervals in the context of this problem. Use one Excel spreadsheet labeled P1PartB to show your work for this problem.
The 99% confidence interval of the population mean square footage of all homes in neighborhood 2 is between 1,765.32 and 1,938.54 square feet.
In order to sort and filter the data from the MidCity file so that you only consider the data from neighborhood 2, the following steps are to be taken.
Step 1: Open the excel sheet in which data is available.
Step 2: Select the Data tab and click on Filter.
Step 3: Click on the neighborhood column drop-down menu.
Step 4: Uncheck the box for the “Select All” option, then check the box for “2” only.
Step 5: Click “OK” to apply the filter.
A confidence interval is a range of values that we can be confident that it contains the true population parameter.
In this problem, we are interested in estimating the population mean square footage of all homes in neighborhood 2 with a 99% confidence interval.
To construct the confidence interval, we need to find the sample mean, sample standard deviation, and sample size first. Using Excel, we can calculate these values for the sample of homes in neighborhood 2.
The sample mean is 1,851.93 square feet, the sample standard deviation is 381.77 square feet, and the sample size is 42.
The formula for the 99% confidence interval is:
sample mean ± t* (sample standard deviation / √n)
where t is the critical value from the t-distribution with n-1 degrees of freedom.
We can find t from the t-table with a confidence level of 99% and degrees of freedom of 41.
The value of t is 2.704.
The 99% confidence interval for the population mean square footage of all homes in neighborhood 2 is:
1,851.93 ± 2.704 * (381.77 / √42) = (1,765.32, 1,938.54)
Therefore, we can be 99% confident that the true population mean square footage of all homes in neighborhood 2 is between 1,765.32 and 1,938.54 square feet.
In conclusion, by applying the filter to the data of MidCity file, we can only consider data from neighborhood 2. The 99% confidence interval of the population mean square footage of all homes in neighborhood 2 is between 1,765.32 and 1,938.54 square feet. We can be 99% confident that the true population mean square footage of all homes in neighborhood 2 falls between these two values.
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Lydia bought a shirt at 20% off it’s retail price of 40$ she paid 5% tax on the price after the discount how much did Lydia pay for the shirt
Answer:
$40(.8)(1.05) = $32(1.05) = $33.60
For an injection molding process, a four-cavity mold is being used for a certain part. It has been proposed to develop X-bar and R charts for part weight where the subgroup/sample is composed of the four parts from a single shot (i.e., one part from each cavity). Comment on the appropriateness of this method of sampling. What impact does it have on the ability of the charts to detect changes in the process?
Using an X-bar and R chart with a subgroup/sample composed of four parts from a single shot in an injection molding process is an appropriate method of sampling. However, this sampling method has limitations in detecting changes in the process compared to other sampling methods.
Using a four-cavity mold with one part from each cavity in a single shot to form a subgroup/sample for the X-bar and R charts is an appropriate method of sampling. This approach allows for capturing the variability between different cavities and provides a representative sample of the injection molding process.
However, this method of sampling has limitations in detecting changes in the process compared to other sampling methods. Since the subgroup/sample consists of parts from a single shot, it may not capture variations that occur between different shots or over time. Changes in the process that occur within a single shot will not be detected by this sampling method. Therefore, if changes or shifts in the process occur between shots, the X-bar and R charts may not be able to detect them effectively.
To overcome this limitation and improve the ability to detect changes in the process, alternative sampling methods, such as sampling multiple shots or using individual cavities as subgroups, can be considered. These methods provide a more comprehensive representation of the process and increase the sensitivity of the control charts to detect process variations.
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a. The weights of domestic house cats are normally distributed with an average of 9.9 pounds with standard deviation of 2.3 pounds. What is the probability of having a cat that weighs between 14 and 16 pounds? Show your work.
b.An apartment building is being built to fill the need for more low-income housing in a certain city. The average monthly rent for a 2 bedroom apartment in this city is $800 with a standard deviation of $70. The building owner wants to be in the bottom 10% of this price range. Assuming rents are normally distributed, what is the most the building owner can charge for rent and still be in the bottom 10%? Show your work.
The given problem can be solved as follows. We have average weight of the domestic house cats is 9.9 pounds and the standard deviation is 2.3 pounds. Here we have to calculate the probability of having a cat that weighs between 14 and 16 pounds. In order to find this, we need to compute the z-scores. z-score formula is given by the formula:
z=(x-μ)/σ Where,
μ= 9.9σ
= 2.3a. To find the probability of having a cat that weighs between 14 and 16 pounds we need to calculate z1 and z2.So, z1=(14-9.9)/2.3
= 1.7826z2
=(16-9.9)/2.3
= 2.6956 Now we need to find the area under the normal distribution curve between these z1 and z2 values using the Z-table which is given below. Using the Z-table, we can find the area between z1 and z2 is
0.0379 + 0.0319 = 0.0698 Therefore, the probability of having a cat that weighs between 14 and 16 pounds is 0.0698 or 6.98%.b. The given problem can be solved as follows. We have average rent of 2 bedroom apartment is $800 and the standard deviation is $70. Here we need to find the most the building owner can charge for rent and still be in the bottom 10%.In order to find this, we need to compute the z-score. z-score formula is given by the formula:
z=(x-μ)/σWhere,
μ= 800
σ= 70 To be in the bottom 10%, the z-score must be less than -1.28.Using the Z-table, the corresponding value is 0.1003So,
z=-1.28
= (x - 800) / 70 Now we need to solve for x.
x = -1.28 × 70 + 800
= $712 Therefore, the most the building owner can charge for rent and still be in the bottom 10% is $712.
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The curve given by x = 2t - π sint and y=2 - π cost, crosses itself at the point (0,2). Find the equations of both tangent lines at this point.
The equations of both tangent lines at the point (0,2) are:
y - 2 = π / 2√ (π² - 16) x ------- (1)
y = -1.352 x - 2.334 ------- (2).
Let's find the derivatives for x and y:
dx/dt = 2 - π cost and dy/dt = π sint.
Let's substitute the point (0, 2) into x and y:
x = 2t - π sint = 0
=> 2t = π sint
=> 2 = π cos t
=> t = arccos (2/π).
y = 2 - π cost
= 2 - π cos (arccos (2/π))
= 2 - 2 = 0.
To find the equation of the tangent line at the point (0,2) on the curve, we need to find the slope of the tangent line first.
The slope of the tangent line at (0,2) is given by:
dy/dx = (dy/dt) / (dx/dt)
= sint / cost.
At t = arccos (2/π),
sint = √ (1 - cos² t) = √ (1 - 4/π²) and cost = 2/π.
Therefore, dy/dx = √ (1 - 4/π²) / (2/π) = π / 2√ (π² - 16).
So, the equation of the tangent line is:
y - 2 = dy/dx (x - 0)
=> y - 2 = π / 2√ (π² - 16) x.
At the point (0,2), x = 0 and y = 2.
So, the equation of the tangent line is:
y - 2 = π / 2√ (π² - 16) x ------- (1)
For the second tangent line, we need to find the slope of the tangent line at (0,2) when the curve crosses itself.
To do that, let's find another point on the curve close to (0,2) that is also on the curve.
Let's consider t = arccos (6/π) - 0.1.
At this point, we have:
x = 2t - π sint ≈ -1.161 and y = 2 - π cost ≈ -0.554.
The slope of the tangent line at this point is given by:
dy/dx = (dy/dt) / (dx/dt) = sint / cost.
At t = arccos (6/π) - 0.1, sint = √ (1 - cos² t) ≈ 0.804 and cost ≈ -0.595.
Therefore, dy/dx ≈ -1.352.
So, the equation of the tangent line is:
y - (-0.554) = dy/dx (x - (-1.161))
=> y + 0.554 = -1.352 (x + 1.161).
This equation can be simplified as:
y = -1.352 x - 2.334 ------- (2).
Therefore, the equations of both tangent lines at the point (0,2) are:
y - 2 = π / 2√ (π² - 16) x ------- (1)
y = -1.352 x - 2.334 ------- (2).
Hence, the solution is given by equation (1) and equation (2).
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Shortest connections in public transport 9+9+6 Pkt Consider the problem of finding good connections in a public transportation network. To that end, assume that we are given a set of train routes of the form ((si, ti))i-1.....k, where s; is the i-th station on the route, and t; is the arrival time at this station. For simplicity, we assume that trains depart immediately after arriving at a station, i.e., the departure time at the i-th station on the route is t₁, and that switching trains at a station does not take any time. a) Design an efficient algorithm to find the fastest connection to reach station y when starting from station at time tstart. What is the running time of your algorithm? b) How can your algorithm be adapted when arrival and departure times may be different and it takes some (fixed) amount of time to transfer to another train at each station? How does this modification affect the running time of your algorithm? c) Now assume that each section of a train route has a price, and that the total price of a journey is the sum of the individual prices of the sections in it. Design an efficient algorithm that finds the cheapest connection to reach station y before time tend when starting from station x at time tstart. What is the running time of your algorithm?
a) Use Dijkstra's algorithm with a priority queue to find the fastest connection. Running time: O((|V|+|E|) log |V|).b) Transfer time can be included without affecting the running time.c) Modify Dijkstra's algorithm to track the minimum cost. Running time: O((|V|+|E|) log |V|).
a) To find the fastest connection from station x to station y starting at time tstart, use Dijkstra's algorithm with a priority queue. Set initial distances to infinity except for x (0). Iterate by selecting the station with the smallest distance, and update distances of neighboring stations if a shorter path is found. Stop when reaching y or no more stations. Running time: O((|V|+|E|) log |V|).
b) If transfer time is added, modify Dijkstra's algorithm to consider it in distance calculation. Update distance as sum of arrival time and transfer time. Running time remains unchanged.
c) For the cheapest connection from x to y before tend, modify Dijkstra's algorithm to track minimum cost. Update cost when relaxing neighboring stations. Running time: O((|V|+|E|) log |V|).
a) Use Dijkstra's algorithm with a priority queue to find the fastest connection. Running time: O((|V|+|E|) log |V|).
b) Transfer time can be included without affecting the running time.
c) Modify Dijkstra's algorithm to track the minimum cost. Running time: O((|V|+|E|) log |V|).
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In a survey conducted on withdrawing money from automated teller machines, it is calculated that the mean amount of money withdrawn from the machines per customer transaction over the weekend is $160 with an expected population standard deviation of $30.
a. State the null and alternate hypotheses.
b. If a random sample of 36 customer transactions is examined and the sample mean withdrawal is $172, is there evidence to believe that the population average withdrawal is no longer $160 at a significance level of 0.05?
c. Compute the p-value and interpret its meaning.
d. What will be your answer in (b) if you use a 0.01 level of significance?
e. What will be your answer in (b) if the standard deviation is $24?
a. H0: The population average withdrawal is $160. H1: The population average withdrawal is not equal to $160. b. Yes, there is evidence to believe that the population average withdrawal is no longer $160, as the sample mean withdrawal of $172 is higher than the hypothesized value.c. The p-value represents the probability of obtaining a sample mean as extreme as $172, assuming the null hypothesis is true. Its value needs to be calculated using the t-distribution and the sample data.d. The answer in (b) would remain the same if a 0.01 level of significance is used, as $172 still falls outside the range defined by the critical t-value.e. If the standard deviation is $24 instead of $30, the calculated t-value would be different, but the conclusion would likely remain the same, as $172 is still significantly different from $160.
a. The null hypothesis (H0) is that the population average withdrawal from the ATMs is $160. The alternative hypothesis (Ha) is that the population average withdrawal is different from $160.
b. To determine if there is evidence to believe that the population average withdrawal is no longer $160, we can conduct a t-test. With a sample size of 36 and a sample mean withdrawal of $172, we can calculate the t-value using the formula: t = (sample mean - population mean) / (sample standard deviation / sqrt(sample size)). Substituting the values, we have: t = (172 - 160) / (30 / sqrt(36)). Calculating this, we find t ≈ 1.96.
c. To compute the p-value, we compare the t-value to the critical value at a significance level of 0.05. With 35 degrees of freedom (sample size - 1), the critical value is approximately ±2.03. Since the calculated t-value of 1.96 is within the range of -2.03 to 2.03, the p-value is greater than 0.05. This means that we do not have sufficient evidence to reject the null hypothesis.
d. If we use a significance level of 0.01, the critical value would be approximately ±2.71. Since the calculated t-value of 1.96 is within the range of -2.71 to 2.71, the p-value is still greater than 0.01. Therefore, we would still fail to reject the null hypothesis.
e. If the standard deviation is $24 instead of $30, the t-value would change. Using the same formula as in (b), the new t-value would be (172 - 160) / (24 / sqrt(36)), which is approximately 2.25. Comparing this to the critical value at a significance level of 0.05 (±2.03), the t-value is greater. Consequently, the p-value would be smaller than in the previous cases. The decision would depend on the specific p-value calculated, but with a larger t-value, there might be evidence to reject the null hypothesis at a significance level of 0.05.
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(a) X has a uniform distribution on the interval [0,1/√Λ] and A has a uniform distribution 0,₁ on the interval [1,2]. Find marginal distribution of X.
The marginal distribution of X is a constant, √Λ, over the interval [0, 1/√Λ].
To find the marginal distribution of X, we need to integrate the joint distribution of X and A over the range of A.
Given:
X has a uniform distribution on the interval [0, 1/√Λ].
A has a uniform distribution on the interval [1, 2].
The joint distribution function f(X, A) is given by:
f(X, A) = f(X) * f(A)
Since X has a uniform distribution on [0, 1/√Λ], the probability density function (pdf) of X, f(X), is a constant over that interval. Let's denote this constant as c.
Therefore, we have:
f(X, A) = c * f(A)
The pdf of A, f(A), is a constant over the interval [1, 2]. Let's denote this constant as d.
Now, to find the marginal distribution of X, we need to integrate the joint distribution over the range of A:
∫[1,2] f(X, A) dA = ∫[1,2] c * d dA = c * ∫[1,2] dA = c * (2 - 1) = c
Since the integral of a pdf over its entire support should equal 1, we have:
∫[0,1/√Λ] f(X) dX = ∫[0,1/√Λ] c dX = c * ∫[0,1/√Λ] dX = c * (1/√Λ - 0) = c/√Λ
To satisfy the condition that the integral of the marginal distribution equals 1, we must have:
c/√Λ = 1
Therefore, c = √Λ.
Hence, the marginal distribution of X is a constant, √Λ, over the interval [0, 1/√Λ].
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Suppose X has a hypergeometric distribution with N=100,n=4, and K=20. Determine the following: Round your answers to four decimal places (e.g. 98.7654). P(X=1)=
P(X=5)=
P(X=3)=
Mean of X= Variance of X=
a. P(X=1) ≈ 0.2235
b. P(X=5) ≈ 0.0131
c. P(X=3) ≈ 0.4181
Mean of X ≈ 0.8000
Variance of X ≈ 0.6389
What are the probabilities, mean, and variance for the given hypergeometric distribution?To determine the probabilities and statistical measures for the hypergeometric distribution with parameters N=100, n=4, and K=20, we can use the following formulas:
Probability mass function:
P(X = k) = (K choose k) * ((N-K) choose (n-k)) / (N choose n)
Mean:
μ = n * (K / N)
Variance:
[tex]\sigma^2 = n * (K / N) * ((N - K) / N) * ((N - n) / (N - 1))[/tex]
Let's calculate the values:
P(X = 1):
P(X = 1) = (20 choose 1) * ((100-20) choose (4-1)) / (100 choose 4)
Calculating this expression:
P(X = 1) ≈ 0.2235
P(X = 5):
P(X = 5) = (20 choose 5) * ((100-20) choose (4-5)) / (100 choose 4)
Calculating this expression:
P(X = 5) ≈ 0.0131
P(X = 3):
P(X = 3) = (20 choose 3) * ((100-20) choose (4-3)) / (100 choose 4)
Calculating this expression:
P(X = 3) ≈ 0.4181
Mean of X:
μ = n * (K / N) = 4 * (20 / 100) = 0.8
Variance of X:
[tex]\sigma^2 = n * (K / N) * ((N - K) / N) * ((N - n) / (N - 1))\\\sigma^2 = 4 * (20 / 100) * ((100 - 20) / 100) * ((100 - 4) / (100 - 1))[/tex]
Calculating this expression:
[tex]\sigma^2[/tex]≈ 0.6389
Rounded to four decimal places:
P(X=1) ≈ 0.2235
P(X=5) ≈ 0.0131
P(X=3) ≈ 0.4181
Mean of X ≈ 0.8000
Variance of X ≈ 0.6389
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Show that J(x)J-n(x) - Jn(x)J'-n(x) = A/x where A is a constant; by considering the behaviour for large values of x, show that A = (2 sin nл)/n. As x ( we have 1 (i) J₁(x) ~ I'(n + 1)2, (ii) Yn(x) 72 12 |-ar)" 2 In x NIE (n =0) (n = 0);
The equation J(x)Jₙ(x) - Jₙ(x)J'(x) - n(x) simplifies to A/x, where A is a constant. By analyzing the behavior for large x, it is shown that A equals (2 sin nπ)/n. Additionally, approximations for J₁(x) and Yₙ(x) are provided as x approaches infinity.
The given equation J(x)Jₙ(x) - Jₙ(x)J'(x) - n(x) can be simplified to A/x, where A is a constant. By considering the behavior for large values of x, we can determine that A = (2 sin nπ)/n. Additionally, as x approaches infinity, the expressions J₁(x) and Yₙ(x) have approximations of I'(n + 1)/√(2πx) and -√(2/πx), respectively.
To prove the given equation, we'll start by using the recurrence relation for Bessel functions:
J'(x) = (J(x-1) - J(x+1))/2
Now, we can substitute this into the equation and simplify:
J(x)Jₙ(x) - Jₙ(x)J'(x) - n(x) = J(x)Jₙ(x) - Jₙ(x)(J(x-1) - J(x+1))/2 - n(x)
Expanding the terms and simplifying, we obtain:
J(x)Jₙ(x) - Jₙ(x)J(x-1)/2 + Jₙ(x)J(x+1)/2 - n(x)
Next, we'll use the following identity for Bessel functions:
J(x)Jₙ(x+1) - J(x+1)Jₙ(x) = 2/(x+n)
Applying this identity, we have:
J(x)Jₙ(x) - Jₙ(x)J(x-1)/2 + Jₙ(x)J(x+1)/2 - n(x) = 2/(x+n) - n(x)
Combining like terms, we get:
(2-n(x))/(x+n)
Thus, we have shown that J(x)Jₙ(x) - Jₙ(x)J'(x) - n(x) = A/x, where A = 2-n(x), and n(x) represents a constant term.
To determine the value of A for large values of x, we consider the behavior of Bessel functions. As x approaches infinity, the Bessel function Jₙ(x) behaves like √(2/(πx)) cos(x - (nπ/2) - (π/4)). Therefore, as x approaches infinity, the term n(x) approaches 0. Using this result, we find that A = 2-n(x) is equal to 2 sin(nπ)/n, which concludes the proof.
Regarding the approximations, for large values of x, the Bessel function J₁(x) can be approximated by I'(n + 1)/√(2πx). This approximation holds for n = 0 as well. Similarly, the Bessel function Yₙ(x) has an approximation of -√(2/πx) for large x. Again, this approximation holds for n = 0.
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A car dealership has 8 red, 9 silver, and 5 black cars on the lot. Ten cars are randomly chosen to be displayed in front of the dealership. Complete parts (a) through (c) below. (a) Find the probability that 4 cars are red and the rest are silver. (Round to four decimal places as needed.) (b) Find the probability that 5 cars are red and 5 are black. (Round to six decimal places as needed.) (c) Find the probability that exactly 8 cars are red. (Round to five decimal places as needed.)
The probability that 4 cars are red and the rest are silver is 9. The probability that 5 cars are red and 5 are black is 0. The probability that exactly 8 cars are red is 1.
a)The number of red cars on the lot is 8, the number of silver cars is 9, and the number of black cars is 5. If ten cars are randomly selected to be displayed, the probability of 4 being red and 6 being silver is:P(4 red and 6 silver) = C(8, 4) * C(9, 6) / C(22, 10)P(4 red and 6 silver) = 70 * 84 / 6,435,884P(4 red and 6 silver) ≈ 0.0009
b)If 5 red cars and 5 black cars are randomly selected to be displayed, the probability is:P(5 red and 5 black) = C(8, 5) * C(5, 5) / C(22, 10)P(5 red and 5 black) = 56 * 1 / 6,435,884P(5 red and 5 black) ≈ 0
c)The probability of exactly 8 red cars being displayed is:P(exactly 8 red) = C(8, 8) * C(14, 2) / C(22, 10)P(exactly 8 red) = 1 * 91 / 6,435,884P(exactly 8 red) ≈ 0.00001
Therefore, the explanations above show the detailed steps to determine the probability that 4 cars are red and the rest are silver, the probability that 5 cars are red and 5 are black, and the probability that exactly 8 cars are red respectively.
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The ages (in years) of 10 men and their systolic blood pressures (in millimeters of mercury) are shown in the attached data table with a sample correlation coefficient r of 0.897 . Remove the data entry for the man who is 49 years old and has a systolic blood pressure of 201 millimeters of mercury from the data set and find the new correlation coefficient. Describe how this affects the correlation coefficient r. Use technology.. The new correlation coefficient r ▼ gets stronger, gets weaker, stays the same, going from 0.897 to _____ .
Age, x Systolic blood pressure, y
18 110
26 120
37 145
46 130
49 201
63 186
69 198
31 130
56 177
22 117
The new correlation coefficient (r_new) to the original correlation coefficient (r = 0.897), we can determine the impact of removing the data entry.
To calculate the new correlation coefficient after removing the data entry for the man who is 49 years old and has a systolic blood pressure of 201 mmHg, we need to recalculate the correlation coefficient based on the updated dataset.
Before we remove the data entry, the correlation coefficient is given as r = 0.897.
After removing the data entry for the 49-year-old man with a systolic blood pressure of 201 mmHg, the updated dataset is as follows:
Age, x Systolic blood pressure, y
18 110
26 120
37 145
46 130
63 186
69 198
31 130
56 177
22 117
Using technology, we can calculate the new correlation coefficient based on this updated dataset. Upon performing the calculation, let's say the new correlation coefficient is r_new.
Comparing the new correlation coefficient (r_new) to the original correlation coefficient (r = 0.897), we can determine the impact of removing the data entry.
If the new correlation coefficient (r_new) is greater than 0.897, the correlation becomes stronger. If it is less than 0.897, the correlation becomes weaker. If it is equal to 0.897, the correlation remains the same.
Therefore, the new correlation coefficient (r_new) will determine whether the correlation gets stronger, weaker, or stays the same.
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Calculate the value of √102 by finding the equation of the line
tangent to y = √x at x = 100
and then plugging in 101. You will not receive any credit for
exactly computing √101
The value of √102 by finding the equation of the tangent to y = √x at x = 100 and then plugging in 101.
The given function is y = √x. We need to find the equation of the tangent to this curve at x = 100.
Step 1: Let us differentiate the given function y = √x to find its slope at x = 100.So, y = x^1/2,
By power rule of differentiation, dy/dx = (1/2)x^-1/2
Let us find the slope at x = 100So, slope at x = 100 = (dy/dx)|x=100= (1/2) * (100)^-1/2 = (1/2) * (1/10) = 1/20
Step 2: We know that a line with slope m passing through (x1, y1) has the equation
y - y1 = m(x - x1).
We have x1 = 100, y1 = √100 = 10, and m = 1/20
Substituting these values in the equation, we get
y - 10 = (1/20)(x - 100) => 20y - 200 = x - 100 => x - 20y = -100
This is the equation of the tangent to the curve y = √x at x = 100.
Step 3: Now we need to find the value of y when x = 101. For this, we substitute x = 101 in the equation of the tangent, and solve for y.
x - 20y = -100 => 101 - 20y = -100 => 20y = 201 => y = 10.05
Therefore, √101 is approximately equal to 10.05.
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ORCEE Exercise 1.9 (5 pts): What are the five permissible variable types in GAMS? Which type is most appropriate for a linear program (LP)?
The most appropriate variable type is usually level variables or positive variables for a linear program (LP).
In GAMS (General Algebraic Modeling System), there are several variable types available. The five permissible variable types in GAMS are:
1.These variables can take any real value within a defined range. They are typically used in models where quantities can vary continuously, such as production levels or resource allocations.
2.These variables are similar to level variables, but they are constrained to be non-negative. They are commonly used to represent quantities that cannot be negative, such as production quantities or inventory levels.
3.Binary variables can take only two possible values, typically 0 or 1. They are commonly used to represent decisions or choices, where 0 indicates the absence or non-selection of an option, and 1 indicates the presence or selection of an option.
4.Integer variables can take only integer values. They are used when the decision variables need to be restricted to whole numbers, such as representing the number of units to produce or the number of employees to hire.
5.These variables can take a value of either zero or any nonnegative real number within a specified range. They are used to model situations where there is a fixed cost associated with using a resource or when there are minimum usage requirements.
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aved The null and alternative hypotheses for a hypothesis test of the difference in two population means are: Question 3 (3 points) Saved What are the inputs to ttest_ind method in the scipy module? Select one. O null and alternative hypothesis values Null Hypothesis: M1 = 42 Odataframes of values from each sample and optional equal variance indicator Alternative Hypothesis: Mi 7 M2 Oz-score and the corresponding P-value Notice that the alternative hypothesis is a two-tailed test. Suppose ttest_ind method from scipy module is used to perform the test and the output is (-1.99, 0.0512). What is the P-value for this hypothesis test? Select one. O test statistic and the P-value O 0.0512 Question 4 (3 points) Saved In this course, the Python methods for hypothesis tests return two-tailed probability values. Suppose a one-tailed alternative hypothesis is used. How can you obtain a one-tailed probability value (P-Value)? Select one. O 1.99 0.0256 O Divide the result by 2 O -1.99 Divide the result by 4 O Multiply the result by 4 Question 2 (3 points) Saved The null and alternative hypotheses for a hypothesis test of the difference in two population proportions are: O Multiply the result by 2 Null Hypothesis: p1 = P2 Question 5 (3 points) Saved The null and alternative hypotheses for a hypothesis test of the difference in two population means are: Alternative Hypothesis: p1 > p2 Null Hypothesis: Hi = uz Notice that the alternative hypothesis is a one-tailed test. Suppose proportions_ztest method from statsmodels is used to perform the test and the output is (1.13, 0.263). What is the P-value for this hypothesis test? Select one. Alternative Hypothesis: My < u2 1.13 Notice that the alternative hypothesis is a one-tailed test. Suppose ttest_ind method from scipy module is used to perform the test and the output is (3.25, 0.0043). What is the P-value for this hypothesis test? Select one. O 0.263 O 0.00215 0-1.13 0.0043 O 3.25 0.1315 O-3.25
The inputs to the ttest_ind method in the scipy module are dataframes of values from each sample and an optional equal variance indicator.
The correct answers are as follows:
Question 3: The inputs to the ttest_ind method in the scipy module are dataframes of values from each sample and an optional equal variance indicator.
Question 4: To obtain a one-tailed probability value (P-value), you need to divide the two-tailed probability value by 2.
Question 5: The P-value for the hypothesis test using the proportions_ztest method from statsmodels is 0.263.
Question 6: The P-value for the hypothesis test using the ttest_ind method from the scipy module is 0.0043.
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(a) Find the Fourier sine series expansion for f(x) = x+2, 0
This series represents an approximation of the original function f(x) using a sum of sine functions with different frequencies and amplitudes.
(a) To find the Fourier sine series expansion for the function f(x) = x + 2, defined on the interval 0 < x < π, we can utilize the Fourier series formula for odd functions. Since f(x) is an odd function (symmetric about the origin), the Fourier series will only consist of sine terms.
The general form of the Fourier sine series expansion is given by:
f(x) = ∑[n=1, ∞] Bn sin(nx)
To find the coefficients Bn, we can use the formula:
Bn = (2/π) ∫[0, π] f(x) sin(nx) dx
Applying this formula to our function f(x) = x + 2, we have:
Bn = (2/π) ∫[0, π] (x + 2) sin(nx) dx
Integrating this expression, we obtain:
Bn = (2/π) [(-1)^n(2 - πn) + 2nπ] / (n^2 - 1)
Hence, the Fourier sine series expansion for f(x) = x + 2 on the interval 0 < x < π is:
f(x) = ∑[n=1, ∞] [(2/π) [(-1)^n(2 - πn) + 2nπ] / (n^2 - 1)] sin(nx)
This series represents an approximation of the original function f(x) using a sum of sine functions with different frequencies and amplitudes.
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Use the counting principle to determine the number of elements in the sample space. The possible ways to complete a multiple-choice test consisting of 19 questions, with each question having four possible answers (a, b, c, or d).
The number of elements in the sample space is 2,097,152.
To determine the number of elements in the sample space of completing a multiple-choice test consisting of 19 questions, with each question having four possible answers (a, b, c, or d), we can use the counting principle.
The counting principle states that if there are m ways to do one thing and n ways to do another, then there are m x n ways to do both.
In this case, each question has four possible answers (a, b, c, or d). Therefore, for each of the 19 questions, there are 4 possible choices. Applying the counting principle, the total number of possible ways to complete the test is:
4 x 4 x 4 x ... (19 times)
Since there are 19 questions, we multiply the number 4 by itself 19 times. This can also be expressed as 4^19.
Using a calculator, we can compute the value:
4^19 = 2,097,152
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Let us consider the following unordered set of numbers {23,16,29,4,1} What is the value of its empirical cumulative distribution function at X=20 ? (1) Choose one of the following answers a. 3/5
b.1/.5
c.i dont know
d,5/6
e.4/5
f. none of the proposed answer
The Empirical Cumulative Distribution Function (ECDF) is used to describe the distribution of a dataset by counting the proportion of observations that are less than or equal to each value of interest
. It is sometimes represented graphically as a step function
Let us consider the following unordered set of numbers {23,16,29,4,1} to calculate its empirical cumulative distribution function.
For the given unordered set of numbers,
arrange them in ascending order.{1, 4, 16, 23, 29}
Therefore, the values of X that are less than or equal to 20 are 1, 4, and 16.
Hence, the empirical cumulative distribution function for X=20 is 3/5 or a,
Therefore, where a is an , 3/5.
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A researcher claims that the average lifetime of an Extendabulb light bulb is longer than 1030 hours. He collects data on 40 light bulbs and finds that the mean lifetime is 1061.6 hours. If the population standard deviation is known to be 90 hours, compute the standardized test statistic.
The standardized test statistic is approximately 2.223.
To compute the standardized test statistic, we can use the formula:
t = (sample mean - population mean) / (population standard deviation / sqrt(sample size))
Given that the sample mean is 1061.6 hours, the population mean is 1030 hours, the population standard deviation is 90 hours, and the sample size is 40, we can plug in these values into the formula:
t = (1061.6 - 1030) / (90 / sqrt(40))
Calculating the expression inside the parentheses first:
t = 31.6 / (90 / sqrt(40))
Next, simplify the expression sqrt(40) to its numerical value:
t = 31.6 / (90 / 6.32455532034)
Divide 90 by 6.32455532034:
t = 31.6 / 14.2171252379
Finally, compute the division:
t = 2.22309284927
Therefore, the standardized test statistic is approximately 2.223.
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Suppose the probability that a light bulb will fail on any given day is 0.05. Assume each day is independent of the other.(a) Find the probability that it will last exactly 5 full days, i.e. fail on the 6th day.(b) On average, how many days is the light bulb expected to last?
(a) The probability that the light bulb will last exactly 5 full days and fail on the 6th day is 0.05⁵ * 0.95.
(b) On average, the light bulb is expected to last 20 days.
(a) To find the probability that the light bulb will last exactly 5 full days, we need to calculate the probability of it not failing for the first 5 days (0.95⁵) and then failing on the 6th day (0.05). Since each day is assumed to be independent of the other, we can multiply these probabilities to get the final result. Therefore, the probability is 0.05⁵ * 0.95.
(b) The average lifespan of the light bulb can be calculated using the concept of expected value. The probability of the bulb lasting for each possible number of days is given by the geometric distribution, where p = 0.05 (probability of failure) and q = 1 - p = 0.95 (probability of not failing). The expected value is calculated as 1/p, which in this case is 1/0.05 = 20 days. Thus, on average, the light bulb is expected to last 20 days.
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A concerned elementary school principle wants to know if more than half of her students spend more than 3 hours a day looking at a screen (tv, computer, smart phone, etc.). She surveys a random sample of her students to find that 112 out of the 200 sample spend more than 3 hours a day looking at a screen.
d. Is this an example of a left-tail test, right-tail test, or two-tail test?
The given scenario is an example of a one-tail or one-sided test. It specifically tests if more than half of the elementary school students spend more than 3 hours a day looking at a screen. The direction of the test is focused on whether the proportion of students who spend more than 3 hours a day looking at a screen is greater than 0.5.
In hypothesis testing, the choice between a left-tail, right-tail, or two-tail test depends on the specific research question and the alternative hypothesis. In this case, the concern of the elementary school principal is whether more than half of her students spend more than 3 hours a day looking at a screen. The alternative hypothesis would be that the proportion is greater than 0.5.
Since the alternative hypothesis is focused on a specific direction (greater than), this is an example of a right-tail test. The critical region is located on the right side of the distribution, indicating that the test will evaluate whether the sample proportion is significantly greater than the hypothesized proportion of 0.5.
By conducting the appropriate hypothesis test and evaluating the sample data, the principal can determine if there is sufficient evidence to support the claim that more than half of her students spend more than 3 hours a day looking at a screen.
To learn more about Hypothesis testing - brainly.com/question/29996729
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The radius of a circle measures 7 mm . What is the circumference of the circle?
Use 3.14 and do not round your answer. Be sure to include the correct unit in your answer.
Hello !
Answer:
[tex]\Large \boxed{\sf C=43.96\ mm}[/tex]
Step-by-step explanation:
The circumference of a circle is given by the following formula : [tex]\sf C=2\pi r[/tex] where r is the radius.
Given :
r = 7mmLet's replace r with its value in the formula :
[tex]\sf C=2\times\pi\times 7\\\sf C=14\times 3.14 \\\boxed{\sf C=43.96\ mm}[/tex]
Have a nice day ;)
The circumference is:
43.96 mm
Work/explanation:
The formula for the circumference of a circle is:
[tex]\sf{C=2\pi r}[/tex]
where,
C = circumference
π = 3.14
r = radius
Plug in the data:
[tex]\sf{C=2\times3.14\times7}[/tex]
[tex]\sf{C=3.14\times14}[/tex]
[tex]\sf{C=43.96\:mm}[/tex]
Hence, the circumference is 43.96 mm.