A company operates four machines during three shifts each day.

| November 19, 2015

Question 2 of 23

1.0 Points

A company operates four machines during three shifts each day. From production records, the data in the table below were collected. At the .05 level of significance test to determine if the number of breakdowns is independent of the shift.

    Machine
    1 2 3
Shift A 41 31 15
B 20 11 17
C 12 9 16
D 16 14 10

A.The number of breakdowns is dependent on the shift, because the test value 11.649 is less than the critical value of 12.592.

B.The claim that the number of breakdowns is independent of the shift cannot be rejected, because the test value 11.649 is less than the critical value of 12.592.

C.The number of breakdowns is dependent on the shift, because the p-value is .07.

D.The number of breakdowns is independent of the shift, because the test value 12.592 is greater than the critical value of 11.649. Reset Selection

Part 2 of 16 –

Question 3 of 23

1.0 Points

If an estimated regression line has a Y-intercept of –7.5 and a slope of 2.5, then when X = 3, the actual value of Y is:

A.10

B.5

C.unknown

D.0 Reset Selection

Question 4 of 23

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) Kilowatts (y)
73 680
78 760
85 910
98 1510
93 1170
81 837
76 600
105 1800

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

B.No, the sample correlation coefficient is equal to 0.981, which does not provide evidence of a significant linear relationship.

C.Yes, the sample correlation coefficient is equal to 0.878, which provides 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 5 of 23

1.0 Points

____________ is/are especially helpful in identifying outliers.

A.Scatterplots

B.Normal curves

C.Linear regression

D.Regression analysis Reset Selection

Part 3 of 16 –

Question 6 of 23

1.0 Points

Serum ferritin is used in diagnosing iron deficiency. In a study conducted recently researchers discovered that in a sample of 28 elderly men the sample standard deviation of serum ferritin was 52.6 mg/L. For 26 younger men the sample standard deviation was 84.2 mg/L. At the .01 level of significance, do these data support the conclusion that the ferritin distribution in elderly men has a smaller variance than in younger men?

A.No, because the test value 1.60 is less than the critical value of 2.54

B.Yes, because the test value 0.390 is less than the critical value 2.54

C.Yes, because the test value 2.56 is greater than the critical value of 2.54

D.Yes, because the test value 2.56 is greater than the critical value 0.394 Reset Selection

Question 7 of 23

1.0 Points

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 = .725, n2 = 21, s2 = .529.

If you compute the test value by placing the larger variance in the numerator, at the .05 level of significance, would you conclude that the risks associated with these two stocks are different?

A.No, the p-value associated with this test is 0.0528

B.No, the test value of 1.879 does not exceed the critical value of 2.46

C.Yes, the p-value associated with this test is 0.0264

D.No, the test value of 1.371 does not exceed the critical value of 2.12 Reset Selection

Part 4 of 16 –

Question 8 of 23

1.0 Points

Results from previous studies showed 79% of all high school seniors from a certain city plan to attend college after graduation. A random sample of 200 high school seniors from this city reveals that 162 plan to attend college. Does this indicate that the percentage has increased from that of previous studies? Test at the 5% level of significance.

What is the p-value associated with your test of hypothesis?

A.0.4874

B.0.2437

C.0.7563

D.0.6874 Reset Selection

Question 9 of 23

1.0 Points

A type II error occurs when:

A.the sample mean differs from the population mean

B.the test is biased

C.the null hypothesis is incorrectly rejected when it is true

D.the null hypothesis is incorrectly accepted when it is false Reset Selection

Question 10 of 23

1.0 Points

Results from previous studies showed 79% of all high school seniors from a certain city plan to attend college after graduation. A random sample of 200 high school seniors from this city reveals that 162 plan to attend college. Does this indicate that the percentage has increased from that of previous studies? Test at the 5% level of significance.

Compute the z or t value of the sample test statistic.

A.z = 0.69

B.t = 1.645

C.z = 0.62

D.z = 1.96 Reset Selection

Part 5 of 16 –

Question 11 of 23

1.0 Points

In constructing a confidence interval estimate for a population mean, when we replace f$sigma f$ with the sample standard deviation (s), we introduce a new source of variability and the sampling distribution we use is:

A.the normal distribution

B.F- distribution

C.t -distribution

D.chi-square distribution Reset Selection

Question 12 of 23

1.0 Points

When you calculate the sample size for a proportion, you use an estimate for the population proportion; namely f$hat{p}f$ . A conservative value for n can be obtained by using f$hat{p}f$ = ______ .

A.0.50

B.0.01

C.0.10

D.0.05 Reset Selection

Part 6 of 16 –

Question 13 of 23

1.0 Points

If Z is a standard normal random variable, then the value z for which P(-z < Z < z) equals 0.8764 is

A.0.3764

B.1.54

C.1.16

D.3.08 Reset Selection

Part 7 of 16 –

Question 14 of 23

1.0 Points

The following data were obtained from a survey of college students. The variable X represents the number of non-assigned books read during the past six months.

x P (X=x)
0 0.2
1 0.25
2 0.2
3 0.15
4 0.1
5 0.1

Find P( Xf$leq f$ 3)

A.0.15

B.0.80

C.0.20

D.0.85 Reset Selection

Part 8 of 16 –

Question 15 of 23

1.0 Points

If two events are mutually exclusive, what is the probability that both occur at the same time?

A.Cannotbe determined from the information given.

B.0.00

C.1.00

D.0.50 Reset Selection

Part 9 of 16 –

Question 16 of 23

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.

Staples, a chain of large office supply stores, sells a line of desktop and laptop computers. Company executives want to know whether the demands for these two types of computers are dependent on one another. Each day’s demand for each type of computers is categorized as Low, Medium-Low, Medium-High, or High. The data shown in the table below is based on 200 days of operation. Based on these data, can Staples conclude that demands for these two types of computers are independent? Test at the 5% level of significance.

desktops

low med-low med-high high

low 3 14 14 4 35

laptops med-low 6 18 17 22 63

med-high 13 16 11 16 56

high 8 14 15 9 46

30 62 57 51 200

What is the test value for this hypothesis test?

Answer: Round your answer to two decimal places.

What is the critical value for this hypothesis test?

Answer: Round your answer to two decimal places.

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

1. At the .05 level of significance, Staples can conclude that demands for these two types of computers are independent.

2. At the .05 level of significance, Staples can conclude that demands for these two types of computers are dependent.

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

Part 10 of 16 –

Question 17 of 23

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
2 10 2.6
3 10 1.8
4 15 2.3
5 15 2.8
6 15 3
7 20 2.7
8 20 3.1
9 20 3.2
10 25 3
11 25 3.3
12 25 3.5

Find the equation of the regression line for these data. What is the value of the coefficient of determination? Place your answer, rounded to 3 decimal places, in the blank. Do not use a dollar sign. For example, 0.345 would be a legitimate entry.

Part 11 of 16 –

Question 18 of 23

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.

Are America’s top chief executive officers (CEOs) really worth all that money? One way to answer this question is to look at the annual company percentage increase in revenue versus the CEO’s annual percentage salary increase in that same company. Suppose that a random sample of companies yielded the following data:

percent change for corporation percent change for CEO
15 6
12 17
3 -4
12 12
28 32
6 -1
8 7
2 2

Do these data indicate that the population mean percentage increase in corporate revenue is greater than the population mean percentage increase in CEO salary? Use a 5% level of significance. 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, 2.345 would be a legitimate entry.

Part 12 of 16 –

Question 19 of 23

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.

Scores on a mathematics examination appear to follow a normal distribution with mean of 65 and standard deviation of 15. The instructor wishes to give a grade of “C” to students scoring between the 60th and 70th percentiles on the exam.

What score represents the 70th percentile score on the mathematics exam? Place your answer in the blank, rounded to a whole number. For example, 62 would be a legitimate entry.

Part 13 of 16 –

Question 20 of 23

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 personnel department of a large corporation wants to estimate the family dental expenses of its employees to determine the feasibility of providing a dental insurance plan. A random sample of 12 employees reveals the following family dental expenses (in dollars): 115, 370, 250, 593, 540, 225, 177, 425, 318, 182, 275, and 228.

Construct a 90% confidence interval estimate for the standard deviation of family dental expenses for all employees of this corporation.

Place your LOWER limit, in dollars rounded to 1 decimal place, in the first blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 123.4 would be a legitimate entry.

Place your UPPER limit, in dollars rounded to 1 decimal place, in the second blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 567.8 would be a legitimate entry.

Part 14 of 16 –

Question 21 of 23

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.

In a survey, 55% of the voters support a particular referendum. If 40 voters are chosen at random, and X is the number of voters that support this referendum, find the mean and variance of X. Place the mean in the first blank and place the variance in the second blank.

Part 15 of 16 –

Question 22 of 23

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.

Suppose a firm that produces light bulbs wants to know whether it can say that its light bulbs typically last more than 1500 hours. Hoping to find support for their claim, the firm collects a random sample of n = 25 light bulbs and records the lifetime (in hours) of each bulb. The information related to the hypothesis test is presented below.

Test of H0: f$muleq f$ 1500 versus H1: f$mu f$ > 1500

Sample mean 1509.5

Std error of mean 4.854

Assuming the life length of this type of lightbulb is normally distributed, if you wish to conduct this test using a .05 level of significance, what is the critical value that you should use? Place your answer, rounded to 3 decimal places in the blank. For example, 1.234 would be a legitimate entry.

Part 16 of 16 –

Question 23 of 23

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.

If a coin is tossed seven times, how many different outcomes are possible? Place your answer in the blank. Do not use any decimal places or commas. For example, 345 would be a legitimate entry.

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