Answer:
Check the explanation
Step-by-step explanation:
All the 5 rows of the coefficient matrix (since it is of order 5×8) will have a pivot position. The augmented matrix obtained by adding a last column of constant terms to the 8 columns of the coefficient matrix will have nine columns and will not have a row of the form [0 0 0 0 0 0 0 0 1]. So the system is consistent.
solve for x round to the nearest tenths
Answer:7.3
Step-by-step explanation:
hypotenuse=h=16
Adjacent=x
Φ=63°
CosΦ=x/h
Cos63=x/16
Cross multiply
16 x cos63=x
Cos63=0.4540
16 x 0.4540=x
7.3=x
x=7.3
Erin built a wooden box to hold hay on her farm. The box is 3 m long, 1 m wide, and 1 m high. Hay costs $14 per cubic meter.
Answer:
It will cost 42 to completely fill the box with hay.
have a good day <3
Plz help
What does “|” mean in mathematical term
Thanks
Answer:
Step-by-step explanation:
If you meant " | ", as in |x|, that's "absolute value." The domain of this function is "all real numbers," and the range is "all real numbers zero or greater."
A company is producing two types of ski goggles. Thirty percent of the production is of type A, and the rest is of type B. Five percent of all type A goggles are returned within 10 days after the sale, whereas only two percent of type B are returned. If a pair of goggles is returned within the first 10 days after the sale, the probability that the goggles returned are of type B is
Answer:
[tex]\dfrac{14}{29}[/tex]
Step-by-step explanation:
Let P(A) be the probability that goggle of type A is manufactured
P(B) be the probability that goggle of type B is manufactured
P(E) be the probability that a goggle is returned within 10 days of its purchase.
According to the question,
P(A) = 30%
P(B) = 70%
P(E/A) is the probability that a goggle is returned within 10 days of its purchase given that it was of type A.
P(E/B) is the probability that a goggle is returned within 10 days of its purchase given that it was of type B.
[tex]P(A \cap E)[/tex] will be the probability that a goggle is of type A and is returned within 10 days of its purchase.
[tex]P(B \cap E)[/tex] will be the probability that a goggle is of type B and is returned within 10 days of its purchase.
[tex]P(E \cap A) = P(A) \times P(E/A)[/tex]
[tex]P(E \cap A) = \dfrac{30}{100} \times \dfrac{5}{100}\\\Rightarrow P(E \cap A) = 1.5 \%[/tex]
[tex]P(E \cap B) = P(B) \times P(E/B)[/tex]
[tex]P(E \cap B) = \dfrac{70}{100} \times \dfrac{2}{100}\\\Rightarrow P(E \cap B) = 1.4 \%[/tex]
[tex]P(E) = 1.5 \% + 1.4 \% \\P(E) = 2.9\%[/tex]
If a goggle is returned within 10 days of its purchase, probability that it was of type B:
[tex]P(B/E) = \dfrac{P(E \cap B)}{P(E)}[/tex]
[tex]\Rightarrow \dfrac{1.4 \%}{2.9\%}\\\Rightarrow \dfrac{14}{29}[/tex]
So, the required probability is [tex]\dfrac{14}{29}.[/tex]
What is the coefficient in yhe expression 10x+8
Answer:
It is x
Step-by-step explanation:
A soda manufacturer claims that its Cherry Fizz soda has more carbonation than a competitor’s Cherry Eclipse soda. Bottles of both types of soda are opened, covered with a balloon, and then shaken. The diameter of each balloon is then measured. The mean balloon diameters are 2.3 inches for the Cherry Fizz soda and 2.1 inches for the Cherry Eclipse soda. A 90 percent confidence interval to estimate the difference in mean diameters, in inches, is (−0.8,1.2). Which of the following claims is supported by the interval?
Answer:
E) Because the interval contains 0, it is possible that there is no difference in mean carbonation levels.
Step-by-step explanation:
Hello!
The soda manufacturer claims that it's Cherry Fizz soda that has more carbonation than the competitor's Cherry Eclipse soda.
To test this claim they compared the carbonation by opening bottles of each soda, covered them with a balloon, and agitated the bottle to release the gas into the ballon. Later the balloon's diameter of each bottle of soda was measured.
Be the variables:
X₁: Diameter of a balloon filled with the gas of a Cherry Fizz soda bottle.
X₂: Diameter of a balloon filled with the gas of a Cherry Eclipse soda bottle.
X[bar]₁= 2.3 inches
X[bar]₂= 2.1 inches
The difference between the two means μ₁-μ₂ was estimated with a 90% CI, obtaining: [-0.8;1.2]inches
Usings 90% confidence level you can expect the interval [-0.8;1.2]inches to include the difference between the diameter of the balloons filled with the gas of the Cherry Fizz soda and the diameter of the balloons filled with the gas of the Cherry Eclipse soda.
The claims are:
A) Because 2.3 inches is larger than 2.1 inches, the manufacturer is correct, and Cherry Fizz has more carbonation.
INCORRECT, the given values are sample measures, you cannot reach any valid conclusions by simply comparing them.
B) Because the interval has more positive than negative values, Cherry Fizz has more carbonation.
INCORRECT, the confidence interval provides a range of values for the estimated parameter, it is equally probable that the parameter is closer to the lower bond, the upper bond, or in the middle of the interval.
C) Because 2.3 and 2.1 are very similar, there is no difference in the mean carbonation levels.
INCORRECT, same as in item A, you cannot reach any valid conclusion by just comparing the sample values, a propper hypothesis test is needed.
D) The interval cannot be interpreted because negative measurements are not possible.
INCORRECT, this interval vas made to estimate the difference between the two means, therefore if one value is less than the other it is possible to observe negative values.
If the CI was to estimate the value of the mean diameter of the balloons of one of the groups, then a negative measurement would be invalid.
E) Because the interval contains 0, there may be no difference in mean carbonation levels.
CORRECT
If you were to test the hypotheses
H₀: μ₁-μ₂=0
H₁: μ₁-μ₂≠0
Using a significance level, complementary to the confidence level used to construct the interval α: 0.1 you can decide whether or not the difference between population means are equal to zero or not.
If the interval contains the zero, then you do not reject the null hypotheses and there is no difference between the population means.
If the interval doesn't include the zero, then you reject the null hypothesis.
I hope this helps!
E) Because the interval contains 0, it is possible that there is no difference in mean carbonation levels.
What will be the answer?
The soda manufacturer claims that it's Cherry Fizz soda that has more carbonation than the competitor's Cherry Eclipse soda.
To test this claim they compared the carbonation by opening bottles of each soda, covered them with a balloon, and agitated the bottle to release the gas into the ballon. Later the balloon's diameter of each bottle of soda was measured.
Be the variables:
X₁: Diameter of a balloon filled with the gas of a Cherry Fizz soda bottle.
X₂: Diameter of a balloon filled with the gas of a Cherry Eclipse soda bottle.
X[bar]₁= 2.3 inches
X[bar]₂= 2.1 inches
The difference between the two means μ₁-μ₂ was estimated with a 90% CI, obtaining: [-0.8;1.2]inches
Usings 90% confidence level you can expect the interval [-0.8;1.2]inches to include the difference between the diameter of the balloons filled with the gas of the Cherry Fizz soda and the diameter of the balloons filled with the gas of the Cherry Eclipse soda.
The claims are:
A) Because 2.3 inches is larger than 2.1 inches, the manufacturer is correct, and Cherry Fizz has more carbonation.
INCORRECT, the given values are sample measures, you cannot reach any valid conclusions by simply comparing them.B) Because the interval has more positive than negative values, Cherry Fizz has more carbonation.
INCORRECT, the confidence interval provides a range of values for the estimated parameter, it is equally probable that the parameter is closer to the lower bond, the upper bond, or in the middle of the interval.C) Because 2.3 and 2.1 are very similar, there is no difference in the mean carbonation levels.
INCORRECT, same as in item A, you cannot reach any valid conclusion by just comparing the sample values, a propper hypothesis test is needed.D) The interval cannot be interpreted because negative measurements are not possible.
INCORRECT, this interval vas made to estimate the difference between the two means, therefore if one value is less than the other it is possible to observe negative values.If the CI was to estimate the value of the mean diameter of the balloons of one of the groups, then a negative measurement would be invalid.
E) Because the interval contains 0, there may be no difference in mean carbonation levels.
CORRECT If you were to test the hypothesesH₀: μ₁-μ₂=0H₁: μ₁-μ₂≠0Using a significance level, complementary to the confidence level used to construct the interval α: 0.1 you can decide whether or not the difference between population means are equal to zero or not.
If the interval contains the zero, then you do not reject the null hypotheses and there is no difference between the population means.
If the interval doesn't include the zero, then you reject the null hypothesis.
Thus the interval contains 0, it is possible that there is no difference in mean carbonation levels.
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Jessica bought the ingredients to make chicken soup, and wanted to make a double batch, which would be 18 cups of soup. A quick Google search told her that this was 259.9 cubic inches. She hoped the soup pot below would be big enough. The soup pot is 9 inches tall with a radius of 3.5 inches. What is the volume of the soup pot? Answer choices are rounded to the nearest tenth cubic inch. 169.6 cubic inches 890.6 cubic inches 197.9 cubic inches 346.4 cubic inches
Answer: 346.4 in^3
Step-by-step explanation:
The pot can be thinked as a cylinder:
The volume of a cylinder is equal to:
V = (pi*r^2)*h
where h is the height, r is the radius and pi = 3.1416
Here we have that: r = 3.5in, h = 9in.
Then the volume is:
V = 3.1416*(3.5in)^2*9in = 346.4in^3
help plz now quick if right brain list
Answer:
c= 5 yards.
Step-by-step explanation:
4*1.5=6
30/6= 5
Complete 12 for 10 points.
Answer:
5 minutes
Step-by-step explanation:
200+15=215
214/43=5
It moved up a total of 200 + 15 = 215 meters at 43 meters per minute
t = 215 m / (43 m/min) = 5 minutes
Answer: 5 minutes
The box plot show the weights, in pounds, of the dogs in two different animal shelters.
Which correctly compares the ranges of the data?
• The range shelter A in 11, and the range in shelter B is 4.
• The range in shelter A is 20, and the range in shelter B is 10.
• The range in shelter A is 13, and the range in shelter B is 8.
• The range in shelter A is 22, and the range in shelter B is 18.
Answer:
The range in shelter A is 22, and the range in shelter B is 18.
Subtract 8 from 30 shelter A which gives you 22. Then subtract 10 from 28 which gives you 18 for Shelter B.
Answer:
The range in shelter A is 22, and the range in shelter B is 18.
Subtract 8 from 30 shelter A which gives you 22. Then subtract 10 from 28 which gives you 18 for Shelter B.
Step-by-step explanation:
Create an equation for the graph Above,Answer should be in y=kx or
y=x+b*
Your answer
Answer:
y=2x
Step-by-step explanation:
Every one x is two y.
Can someone answer I barely have any points now :(
A. True, a rhombus is a parallelogram with equal sides. A rhombus has four congruent sides.
B. True, but there are two other ways to find the area of a rhombus: there is the "diagonals" method and the "trigonometry" method.
C. False, the area of a rhombus is not less than the area of a parallelogram because it will depend on the diagonals.
D. False, a parallelogram is not always a rhombus because the dimensions and other attributes of a parallelogram may vary while the rhombus will remain equal for all aspects.
E. True, if you use the base times height formula but if you used any of the other formulas this would be false.
Every year, census researchers collect data from 850 public and private hospitals across the United States. Which issue will invalidate the conclusion of the hypothesis test? Group of answer choices The data comes from only 850 hospitals in the U.S. when there are 5,700 hospitals in the U.S. Researchers received more data from public hospitals than from private hospitals. The data is selected by choosing the first 850 hospitals from an alphabetized list.
Answer:
Option C
Step-by-step explanation:
For a better, clear and unbiased sampling, choosing randomly might not allow for a biased sampling. Choosing in an alphabetical order might not give a representative of the whole hospitals both private and public, thus invigilator the conclusion of our hypothesis test.
A store sells gift cards in preset amounts. You can purchase gift cards for $20 or $30. You have spent $680 on gift cards. Write an equation in standard form to represent this situation. What are three combinations of gift cards you could have purchased?
Let x be the number of gift cards for $20, and let y be the number of gift cards for $30. Write an equation in standard form to represent this situation
Answer:
20x + 30y = 680
Step-by-step explanation:
Give me a good rating please!
An equation is a mathematical statement that is made up of two expressions connected by an equal sign.
The equation represents the number of $20 and $30 gift cards bought.
20x + 30y = 680
What is an equation?An equation is a mathematical statement that is made up of two expressions connected by an equal sign.
We have,
Number of gift cards for $20 = x
Number of gift cards for $30 = y
Total amount spend on gift card = $680
The equation represents the number of $20 and $30 gift cards bought.
20x + 30y = 680
Thus,
The equation represents the number of $20 and $30 gift cards bought.
20x + 30y = 680
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A mirror frame in the shape of an oval is shown below. The ends of the frame form semicircles: (5 points)
An oval is formed by a rectangle with semicircles at each end. The length of the rectangle is 62 inches. The width of the rectangle is 27 inches.
Which of the following is the perimeter of the inner edge of the frame?
Answer:
696.265 inches
Step-by-step explanation:
Radius = 27/2 = 13.5
2 semicircles + 2 lengths
(3.14 × 13.5²) + 2(62)
696.265 inches
Answer:
696
Step-by-step explanation:
The management of Discount Furniture, a chain of discount furniture stores in the Northeast, designed an incentive plan for salespeople. To evaluate this innovative plan, 12 salespeople were selected at random, and their weekly incomes before and after the plan were recorded. Was there a significant increase in the typical salesperson’s weekly income due to the innovative incentive plan? Use the .05 significance level. Estimate the p-value, and interpret it
Answer:
Step-by-step explanation:
The question is incomplete. The complete question is
The management of Discount Furniture, a chain of discount furniture stores in the Northeast, designed an incentive plan for salespeople. To evaluate this innovative plan, 12 salespeople were selected at random, and their weekly incomes before and after the plan were recorded.
Salesperson Before After
Sid Mahone $320 $340
Carol Quick 290 285
Tom Jackson 421 475
Andy Jones 510 510
Jean Sloan 210 210
Jack Walker 402 500
Peg Mancuso 625 631
Anita Loma 560 560
John Cuso 360 365
Carl Utz 431 431
A. S. Kushner 506 525
Fern Lawton 505 619
Solution:
Corresponding income of salespersons before and after form matched pairs.
The data for the test are the differences between the income is salespersons.
μd = the income before minus their income after.
Bedore after diff
320 340 -20
290 285 5
421 475 - 54
510 510 0
210 210 0
402 500 - 98
625 631 -6
569 560 0
360 365 - 5
431 431 0
506 525 - 19
505 619 - 114
Sample mean, xd
= (- 20 + 5 - 54 + 0 + 0 - 98 - 6 + 0 - 5 + 0 + - 19 - 114)/12 = - 25.92
xd = - 25.92
Standard deviation = √(summation(x - mean)²/n
n = 12
Summation(x - mean)² = (- 20 + 25.92)^2 + (5 - 25.92)^2 + (- 54 + 25.92)^2+ (0 + 25.92)^2 + (0 + 25.92)^2 + ( - 98 + 25.92)^2 + ( - 6 + 25.92)^2 + (0 + 25.92)^2 + (- 5 + 25.92)^2 + (0 + 25.92)^2 + (- 19 + 25.92)^2 + (- 114 + 25.92)^2 = 17784.5168
Standard deviation = √(17784.5168/12
sd = 38.5
For the null hypothesis
H0: μd ≥ 0
For the alternative hypothesis
H1: μd < 0
1) The distribution is a students t. Therefore, degree of freedom, df = n - 1 = 12 - 1 = 11
2) The formula for determining the test statistic is
t = (xd - μd)/(sd/√n)
t = ( - 25.92- 0)/(38.5/√12)
t = - 2.33
3) We would determine the probability value by using the t test calculator.
p = 0.02
4) Assume alpha = 0.05
Since alpha, 0.05 > than the p value, 0.02, then we would reject the null hypothesis. We can conclude that at 5% significance level, there is a significant increase in the typical salesperson’s weekly income due to the innovative incentive plan
Convert the polar coordinates to rectangular form (√2,-π\4)
Answer:
(1, -1)
Step-by-step explanation:
To convert polar to rectangular coordinates, use these identities:
x = rcos(Ф)y = rsin(Ф)x² + y² = r²Here we were given the point [tex](\sqrt{2},-\frac{\pi}{4})[/tex] which is our (r, Ф) point
We can now plug these values into our x and y equations to convert to rectangular and find our (x, y) point
x = [tex](\sqrt{2} )cos(-\frac{\pi}{4} )= (\sqrt{2})(\frac{\sqrt{2} }{2})=\frac{2}{2}=1[/tex] y = [tex](\sqrt{2} )sin(-\frac{\pi}{4} )= (\sqrt{2})(-\frac{\sqrt{2} }{2})=-\frac{2}{2}=-1[/tex]So our (x, y) point is (1, -1)
[tex](\sqrt{2},-\frac{\pi}{4}) = (1, -1)[/tex]Mrs. McAlister wrote the equation 10t-4t+3t=8 on the board and asked students to write equivalent equations.
As we solve we generate a succession of equivalent equations.
10t - 4t + 3t = 8
9t = 8
t = 8/9
Answer:
10t-4t+3t=8
t (10-4+3)=8
t (9)=8
9t=8
t=8/9
Step-by-step explanation:
In the question stated above, the common factor amongst the numbers with the variables is t, therefore we factorise the t out of the numbers, hence leaving t outside the bracket. After we solve the equation of the simple numbers of which the product is 9. After this we already know the 9 is to be multiplied by the t to make it 9t=8. We divide both side by the 9 and get a result of t=8/9
Which fraction equals a repeating decimal?
30/50
13/25
5/30
13/10
Answer:
5/30
Step-by-step explanation:
5/30 = 1/6 =0.166666666...
The fraction equals a repeating decimal is 5/30.
What are decimals?A decimal numeral system is the standard system for denoting integer and non-integer numbers. The way of denoting numbers in the decimal system is often referred to as decimal notation.
Now the given fractions are,
30/50
13/25
5/30
13/10
Converting them into decimals we get,
30/50 = 0.6
13/25 = 0.52
5/30 = 0.1666..
13/10 = 1.3
Thus the repeating decimal is 0.1666..
So, the fraction with repeating decimal is 5/30 = 0.1666..
Thus, the fraction equals a repeating decimal is 5/30.
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Alice and Bob share some money in the
ratio 7:5. Alice got £4 more than Bob. How
much did Alice get?
Answer:
14
Step-by-step explanation:
7-5 = 2
4/2 = 2
2 x 7 = 14
Harris Interactive® conducted a poll of American adults in August of 2011 to study the use of online medical information. Of the 1,019 randomly chosen adults, 60% had used the Internet within the past month to obtain medical information. Use the results of this survey to create an approximate 95% confidence interval estimate for the percentage of all American adults who have used the Internet to obtain medical information in the past month.
Answer:
[tex]0.60 - 1.96\sqrt{\frac{0.60(1-0.60)}{1019}}=0.570[/tex]
[tex]0.60 + 1.96\sqrt{\frac{0.60(1-0.60)}{1019}}=0.630[/tex]
The 95% confidence interval for the true proportion would be given by (0.570;0.630) .
And if we convert this into % we got (57.0%, 63.0%)
Step-by-step explanation:
The information given we have the following info given:
[tex] n = 1019[/tex] represent the sampel size
[tex] \hat p=0.6[/tex] represent the sample proportion of interest
The confidence level is 95%, our significance level would be given by [tex]\alpha=1-0.95=0.05[/tex] and [tex]\alpha/2 =0.025[/tex]. And the critical value would be given by:
[tex]z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96[/tex]
The confidence interval for the mean is given by the following formula:
[tex]\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}[/tex]
Replacing the info given we got:
[tex]0.60 - 1.96\sqrt{\frac{0.60(1-0.60)}{1019}}=0.570[/tex]
[tex]0.60 + 1.96\sqrt{\frac{0.60(1-0.60)}{1019}}=0.630[/tex]
The 95% confidence interval for the true proportion would be given by (0.570;0.630) .
And if we convert this into % we got (57.0%, 63.0%)
help please quick 100 points quick tell me what to write please if you now how to do this
Answer:
8 footballs
18 basketballs
36 baseballs
24 softballs
Step-by-step explanation:
Let f = footballs
f = 8
Let b = basketballs
b = 2+2f = 2 +2(8) = 2 +16 = 18
Let B = baseballs
B = 5f -4 = 5(8) -4 = 40-4 = 36
Let s = softballs
s = 6+1/2B = 6+1/2(36) = 6+18 = 24
The total is 86
f+b+B +s = 86
8+18+36+24 = 86
86=86
There are 8 footballs.
Two more than twice the number of footballs are basketballs:
2f + 2 = b
f = number of footballs
b = number of basketballs
In the first statement, there are 8 footballs. So, f = 8
2(8) + 2 = b
16 + 2 = b
18 = b
Therefore, there are 18 basketballs.
Four less than 5 times the number of footballs are baseballs:
5f - 4 = a
f = number of footballs
a = number of baseballs
In the first statement, there are 8 footballs. So, f = 8
5(8) - 4 = a
40 - 4 = a
36 = a
Therefore, there are 36 baseballs.
Six more than half of the baseballs are softballs:
a/2 + 6 = s
a = number of baseballs
s = number of softballs
In the third statement, there are 36 baseballs. So, a = 36
(36)/2 + 6 = s
18 + 6 = s
24 = s
Therefore, there are 24 softballs.
Best of Luck!
00:00
Hei has the element shown for his science experiment. How many kilograms of the material does he have?
(1.000 grams = 1 kilogram)
Copper
3,508 g
350.8 kilograms
35.08 kilograms
3.508 kilograms
0.3508 kilograms
Answer:
3.508 kilograms
Step-by-step explanation:
This question can be solved using a rule of three.
We have that each kilogram is 1000 grams. How many kilograms are there for 3508 grams?
1kg - 1000g
xkg - 3508g
[tex]1000x = 3508[/tex]
[tex]x = \frac{3508}{1000}[/tex]
[tex]x = 3.508[/tex]
So the correct answer is:
3.508 kilograms
Identity the conic section whose equation is R=1/(2-3sinx)
Answer:
hyperbola
Step-by-step explanation:
A graphing calculator shows the equation is that of a hyperbola.
__
Multiplying by the denominator gives ...
r(2 -3sin(x)) = 1
2r -3y = 1 . . . . . . . . substituting y=r·sin(x)
2r = 1 +3y . . . . . . . .isolating r
4r² = 1 +6y +9y² . . squaring both sides
4(x² +y²) = 1 +6y +9y² . . . . . substituting x²+y² = r²
4x² -5y² -6y -1 = 0 . . . . . . . . general form equation of a hyperbola
What point appears to be the solution to the system of
equations shown in the graph?
Answer:
x = -2
y= -5
is the solution of the system of equations
BRAINLIST+11 Pts!!!
Jim just found a job with a take-home pay of $950 per month. He must pay $400 for rent and $100 for groceries each month. He also spends $100 per month on transportation. If he budgets $50 each month for clothing, $100 for restaurants and $50 for everything else, how long will it take him to save $1,800?
Answer:12 months
Step-by-step explanation:
400+400=800 so 950-800=150 1800/150=12
7y - 2y + 8 = 19 + 4y
Jose invests $4000 in an investment account paying 8% annually for 12 years. Suppose the interest was compounded quarterly instead of annually.
How much would the future value of the investment increase?
Enter your answer as a dollar amount, such as: $302.26
Answer:
$275.6
Step-by-step explanation:
Compound interest:
The compound interest formula is given by:
[tex]A(t) = P(1 + \frac{r}{n})^{nt}[/tex]
Where A(t) is the amount of money after t years, P is the principal(the initial sum of money), r is the interest rate(as a decimal value), n is the number of times that interest is compounded per unit year and t is the time in years for which the money is invested or borrowed.
In this question:
[tex]P = 4000, r = 0.08, t = 12[/tex]
Anually:
[tex]n = 1[/tex]
Then
[tex]A(t) = P(1 + \frac{r}{n})^{nt}[/tex]
[tex]A(12) = 4000(1 + \frac{0.08}{1})^{12}[/tex]
[tex]A(12) = 10072.68[/tex]
Quarterly:
[tex]n = 4[/tex]
Then
[tex]A(t) = P(1 + \frac{r}{n})^{nt}[/tex]
[tex]A(12) = 4000(1 + \frac{0.08}{2})^{12*4}[/tex]
[tex]A(12) = 10348.28[/tex]
How much would the future value of the investment increase?
10348.28 - 10072.68 = 275.6
The future value of the investment would increase by $275.6.
The overhead reach distances of adult females are normally distributed with a mean of 197.5 cm197.5 cm and a standard deviation of 8.3 cm8.3 cm. a. Find the probability that an individual distance is greater than 210.90210.90 cm. b. Find the probability that the mean for 1515 randomly selected distances is greater than 196.00 cm.196.00 cm. c. Why can the normal distribution be used in part (b), even though the sample size does not exceed 30?
Answer:
a) 5.37% probability that an individual distance is greater than 210.9 cm
b) 75.80% probability that the mean for 15 randomly selected distances is greater than 196.00 cm.
c) Because the underlying distribution is normal. We only have to verify the sample size if the underlying population is not normal.
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the central limit theorem.
Normal probability distribution
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
Central Limit Theorem
The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
In this question, we have that:
[tex]\mu = 197.5, \sigma = 8.3[/tex]
a. Find the probability that an individual distance is greater than 210.9 cm
This is 1 subtracted by the pvalue of Z when X = 210.9. So
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{210.9 - 197.5}{8.3}[/tex]
[tex]Z = 1.61[/tex]
[tex]Z = 1.61[/tex] has a pvalue of 0.9463.
1 - 0.9463 = 0.0537
5.37% probability that an individual distance is greater than 210.9 cm.
b. Find the probability that the mean for 15 randomly selected distances is greater than 196.00 cm.
Now [tex]n = 15, s = \frac{8.3}{\sqrt{15}} = 2.14[/tex]
This probability is 1 subtracted by the pvalue of Z when X = 196. Then
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
By the Central Limit Theorem
[tex]Z = \frac{X - \mu}{s}[/tex]
[tex]Z = \frac{196 - 197.5}{2.14}[/tex]
[tex]Z = -0.7[/tex]
[tex]Z = -0.7[/tex] has a pvalue of 0.2420.
1 - 0.2420 = 0.7580
75.80% probability that the mean for 15 randomly selected distances is greater than 196.00 cm.
c. Why can the normal distribution be used in part (b), even though the sample size does not exceed 30?
The underlying distribution(overhead reach distances of adult females) is normal, which means that the sample size requirement(being at least 30) does not apply.
2. Inflation is at a rate of 7% per year. Evan's favorite bread now costs $1.79. What did it cost 10 years ago? How long
before the cost of the bread doubles?
Answer:
It cost $0.91 10 years ago.
It takes 10.24 years for the cost of bread to double.
Step-by-step explanation:
The equation for the price of bread after t years has the following format:
[tex]P(t) = P(0)(1+r)^{t}[/tex]
In which P(0) is the current price, and r is the inflation rate, as a decimal.
If we want to find the price for example, 10 years ago, we find P(-10).
Inflation is at a rate of 7% per year. Evan's favorite bread now costs $1.79.
This means that [tex]r = 0.07, P(0) = 1.79[/tex]. So
[tex]P(t) = P(0)(1+r)^{t}[/tex]
[tex]P(t) = 1.79(1+0.07)^{t}[/tex]
[tex]P(t) = 1.79(1.07)^{t}[/tex]
What did it cost 10 years ago?
[tex]P(-10) = 1.79(1.07)^{-10} = 0.91[/tex]
It cost $0.91 10 years ago.
How long before the cost of the bread doubles?
This is t for which P(t) = 2P(0) = 2*1.79. So
[tex]P(t) = 1.79(1.07)^{t}[/tex]
[tex]2*1.79 = 1.79(1.07)^{t}[/tex]
[tex](1.07)^{t} = 2[/tex]
[tex]\log{(1.07)^{t}} = \log{2}[/tex]
[tex]t\log{1.07} = \log{2}[/tex]
[tex]t = \frac{\log{2}}{\log{1.07}}[/tex]
[tex]t = 10.24[/tex]
It takes 10.24 years for the cost of bread to double.
