Stats Questions 2

Part 1 of 8 -

Question 1 of 17 1.0 Points

A pharmaceutical company is testing the effectiveness of a new drug for lowering cholesterol. As part of

this trial, they wish to determine whether there is a difference between the effectiveness for women and

for men. Assume α = 0.05. What is the test value?

Women Men

Sample size 50 80

Mean effect 7 6.95

Sample variance 3 4

A.t = 0.151

B.z = 0.081

C.t = 3.252

D.z = 0.455

Reset Selection

Question 2 of 17 1.0 Points

Q-Mart is interested in comparing its male and female customers. Q-Mart would like to know if the

amount of money spent by its female charge customers differs, on average, from the amount spent by its

male charge customers.

To answer this question, an analyst collected random samples of 25 female customers and 22 male

customers. Based on these samples, on average, the 25 women charge customers spent $102.23 and

the 22 men charge customers spent $86.46. Moreover, the sample standard deviation of the amount

charged by the 25 women was $93.393, and the sample standard deviation of the amount charged by

the 22 men was $59.695.

Using the procedure advocated by Bluman, at the 10% level of significance, is there sufficient evidence

for Q-Mart to conclude that, on average, the amount spent by women charge customers differs from the

amount spent by men charge customers.

A.Yes, the p-value of this test is greater than 0.10

B.Yes, the test value does not exceed the critical value

C.No, the test value does not exceed the critical value.

D.No, the p-value of this test is less than 0.10.

Reset Selection

Question 3 of 17 1.0 Points

Some defendants in criminal proceedings plead guilty and are sentenced without a trial, whereas others who

plead innocent are subsequently found guilty and then are sentenced. In recent years, legal scholars

have speculated as to whether sentences of those who plead guilty differ in severity from sentences for

those who plead innocent and are subsequently judged guilty. Consider the data given below on

defendants accused of robbery, all of whom, by the way, had previous prison records. At the .01 level of

significance, do these data suggest that the proportion of all defendants in these circumstances who

plead guilty and are sent to prison differs from the proportion who are sent to prison after pleading

innocent and being found guilty?

Plea

Guilty Not Guilty

Number judged guilty n1 = 191 n2 = 64

Number sentenced to prison x1 = 101 x2 = 56

Sample proportion .529 .875

A.Yes, because the test value -4.94 is outside the interval (-2.58, 2.58)

B.No, because the test value -4.94 is outside the interval (-1.96, 1.96)

C.No, because the test value -1.96 is inside the interval (-2.58, 2.58)

D.Yes, because the test value 2.58 is inside the interval (-4.94, 4.94)

Reset Selection

Part 2 of 8 -

Question 4 of 17 1.0 Points

____________ is/are especially helpful in identifying outliers.

A.Normal curves

B.Regression analysis

C.Scatterplots

D.Linear regression

Reset Selection

Question 5 of 17 1.0 Points

The correlation value ranges from

A.0 to +1

B.–2 to +2

C.-3 to +3

D.–1 to +1

Reset Selection

Question 6 of 17 1.0 Points

The marketing manager of a large supermarket chain would like to use shelf space to predict the sales of

pet food. For a random sample of 12 similar stores, she gathered the following information regarding the

shelf space, in feet, devoted to pet food and the weekly sales in hundreds of dollars. .

Store 1 2 3 4 5 6

Shelf Space 5 5 5 10 10 10

Weekly Sales 1.6 2.2 1.4 1.9 2.4 2.6

Store 7 8 9 10 11 12

Shelf Space 15 15 15 20 20 20

Weekly Sales 2.3 2.7 2.8 2.6 2.9 3.1

Compute the value of the sample correlation coefficient between weekly sales and shelf space.

A.0.827

B.0.652

C.0.308

D.0.684

Reset Selection

Question 7 of 17 1.0 Points

The city of Oakdale wishes to see if there is a linear relationship between the temperature and the amount of

electricity used (in kilowatts). Based on the data in the table below, is there a significant linear

relationship between temperature and the amount of electricity used? These data are also available in

the worksheet temperature in the Excel workbook Temperature.xlsx.

Temperature.xlsx

Temperature (x) 73 78 85 98 93 81 76 105

Kilowatts (y) 680 760 910 1510 1170 837 600 1800

A.No, the sample correlation coefficient is equal to 0.098, which does not provide evidence of a

significant linear relationship.

B.Yes, the sample correlation coefficient is equal to 0.878, which provides evidence of a significant

linear relationship.

C.No, the sample correlation coefficient is equal to 0.981, which does not provide evidence of a

significant linear relationship.

D.Yes, the sample correlation coefficient is equal to 0.981, which provides evidence of a significant

linear relationship.

Reset Selection

Question 8 of 17 1.0 Points

The standard error of the estimate, sest, is essentially the

A.standard deviation of the residuals

B.mean of the residuals

C.mean of the explanatory variable

D.standard deviation of the explanatory variable

Reset Selection

Part 3 of 8 -

Question 9 of 17 2.0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces

(e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific

notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A field researcher is gathering data on the trunk diameters of mature pine and spruce trees in a certain

area. The following are the results of his random sampling. Can he conclude, at the 0.10 level of

significance, that the average trunk diameter of a pine tree is greater than the average diameter of a

spruce tree?

Pine trees Spruce trees

Sample size 20 30

Mean trunk diameter (cm) 45 39

Sample variance 100 150

What is the test value for this hypothesis test?

Test value: Round your answer to three decimal places.

What is the critical value?

Critical value: Round your answer to three decimal places.

Part 4 of 8 -

Question 10 of 17 1.0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces

(e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific

notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The marketing manager of a large supermarket chain would like to determine the effect of shelf space (in

feet) on the weekly sales of international food (in hundreds of dollars). A random sample of 12 equal –

sized stores is selected, with the following results:

Store Shelf Space(X) Weekly Sales(Y)

1 10 2.0

2 10 2.6

3 10 1.8

4 15 2.3

5 15 2.8

6 15 3.0

7 20 2.7

8 20 3.1

9 20 3.2

10 25 3.0

11 25 3.3

12 25 3.5

Using the equation of the regression line for these data, predict the average weekly sales (in hundreds of

dollars) of international food for stores with 13 feet of shelf space for international food.

Place your answer, rounded to 3 decimal places , in the blank. Do not use a dollar sign. For example,

2.345 would be a legitimate entry.

Question 11 of 17 1.0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces

(e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific

notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A company has observed that there is a linear relationship between indirect labor expense (ILE) , in

dollars, and direct labor hours (DLH). Data for direct labor hours and indirect labor expense for 18 months

are given in the file ILE_and_DLH.xlsx

Treating ILE as the response variable, use regression to fit a straight line to all 18 data points.

Using your estimated regression output, predict the indirect labor expenses for a month in which the

company has 31 direct labor hours.

Place your answer, rounded to 1 decimal place, in the blank. Do not use any stray punctuation marks or

a dollar sign. For example, 458.9 would be a legitimate entry.

Part 5 of 8 -

Question 12 of 17 1.0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces

(e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific

notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

An investor wants to compare the risks associated with two different stocks. One way to measure the risk

of a given stock is to measure the variation in the stock’s daily price changes.

In an effort to test the claim that the variance in the daily stock price changes for stock 1 is different from

the variance in the daily stock price changes for stock 2, the investor obtains a random sample of 21

daily price changes for stock 1 and 21 daily price changes for stock 2.

The summary statistics associated with these samples are: n1 = 21, s1 = .848, n2 = 21, s2 = .529.

If you follow Bluman's advice and place the larger variance in the numerator when computing the test

value, at the .05 level of significance, what is the critical value associated with this test of hypothesis?

Place your answer, rounded to 2 decimal places, in the blank. For example, 3.45 would be a legitimate

entry.

Question 13 of 17 1.0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces

(e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific

notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

Q-Mart is interested in comparing its male and female customers. Q-Mart would like to know if the

amount of money spent by its female charge customers differs, on average, from the amount spent by its

male charge customers. To answer this question, an analyst collected random samples of 25 female

customers and 22 male customers.

Based on these samples, on average, the 25 women charge customers spent $102.23 and the 22 men

charge customers spent $86.46. Moreover, the sample standard deviation of the amount charged by the

25 women was $93.393, and the sample standard deviation of the amount charged by the 22 men was

$59.695.

Suppose, using a 10% level of significance, you wish to know if there is sufficient evidence for Q-Mart to

conclude that, on average, the amount spent by women charge customers differs from the amount spent

by men charge customers. That is suppose you wish to test

H0: versus H1:

Assuming that the amounts spent by male and female charge customers at Q-Mart are normally

distributed, based on the procedure advocated by Bluman, what is the test value that you would use to

conduct this test of hypothesis? Place your answer, rounded to 3 decimal places, in the blank. For

example, 0.123 would be a legitimate entry.

Part 6 of 8 -

Question 14 of 17 3.0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces

(e.g., as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific

notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

Researchers conducted an experiment to measure the effect of a drug on improving the quality of sleep

as determined by how many more minutes of REM sleep were measured for each participant. One group

of participants were given the experimental drug; the other (control) group was given a placebo. Does the

evidence indicate that the drug improved the amount of REM sleep at a 0.01 level of significance?

Answer each of the following parts.

Experimental group Control group

sample size 35 50

mean sleep improvement 12.8 9.1

sample variance 56.3 61.2

What is the test value for this hypothesis test?

Answer: Round your answer to two decimal places.

What is the P-value for this hypothesis test?

Answer: Round your answer to three decimal places.

What is the conclusion of this hypothesis test? Choose one.

1. There is sufficient evidence to show that the experimental drug improved the quality of sleep.

2. There is not sufficient evidence to show that the experimental drug improved the quality of sleep.

3. There is sufficient evidence to show that the quality of sleep is different for the experimental drug than

for the control drug.

4. There is not sufficient evidence to show that the control drug decreased the quality of sleep.

Answer: Enter only a 1, 2, 3 or 4 for your answer.

Part 7 of 8 -

Question 15 of 17 1.0 Points

When the necessary conditions are met, a two-tail test is being conducted to test the difference between

two population proportions. The two sample proportions are = 0.35 and = 0.42, and the standard

error of the sampling distribution of is 0.054. The calculated value of the test statistic is

1.2963.

True

False

Reset Selection

Part 8 of 8 -

Question 16 of 17 1.0 Points

In a simple linear regression problem, the least squares line is y' = -3.2 + 1.3X, and the coefficient of

determination is 0.7225. The coefficient of correlation must be –0.85.

True

False

Reset Selection

Question 17 of 17 1.0 Points

In simple linear regression analysis, the relationship between the response variable Y and the

explanatory variable X is a straight line. This means that all data points lie on the line.

True

False

Reset Selection