Question 1

2pts

From a random sample of 58 businesses, it is found that the mean time the owner spends on administrative issues each week is 21.69 with a population standard deviation of 3.23. What is the 95% confidence interval for the amount of time spent on administrative issues?

Group of answer choices

(20.86, 22.52)

(20.71, 22.67)

(21.78, 22.60)

(19.24, 24.14)

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Question 2

2pts

If a confidence interval is given from 45.82 up to 55.90 and the mean is known to be 50.86, what is the margin of error?

Group of answer choices

10.08

5.04

2.52

45.82

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Question 3

2pts

If a shirt manufacturer wanted to make shirts that fit most individuals, what characteristics would be better?

Group of answer choices

wide confidence interval so shirts fit most individuals

narrow confidence interval so shirts fit most individuals

narrow confidence interval so shirts fit few individuals

wide confidence interval so shirts fit few individuals

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Question 4

2pts

Which of the following are most likely to lead to a wide confidence interval?

Group of answer choices

large standard deviation

small standard deviation

large mean

large sample size

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Question 5

2pts

If you were designing a study that would benefit from very disperse data points, you would want the input variable to have:

Group of answer choices

a large sample size

a large mean

a large standard deviation

a small margin of error

Question 6

2pts

The 95% confidence interval for these parts is 56.98 to 57.05 under normal operations. A systematic sample is taken from the manufacturing line to determine if the production process is still within acceptable levels. The mean of the sample is 57.06. What should be done about the production line?

Group of answer choices

Keep the line operating as it is close to the confidence interval

Stop the line as it is close to the confidence interval

Keep the line operating as it is outside the confidence interval

Stop the line as it is outside the confidence interval

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Question 7

2pts

In a sample of 41 temperature readings taken from the freezer of a restaurant, the mean is 29.7 degrees and the population standard deviation is 2.7 degrees. What would be the 80% confidence interval for the temperatures in the freezer?

Group of answer choices

(29.16, 30.24)

(24.30, 35.10)

(31.36, 32.44)

(27.00, 32.4)

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Question 8

2pts

What is the 99% confidence interval for a sample of 36 seat belts that have a mean length of 85.6 inches long and a population standard deviation of 2.9 inches?

Group of answer choices

(84.6, 86.5)

(82.7, 88.5)

(84.4, 86.8)

(84.8, 86.4)

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Question 9

2pts

If two samples A and B had the same mean and sample size, but sample B had a larger standard deviation, which sample would have the wider 95% confidence interval?

Group of answer choices

Sample B as it has the smaller sample

Sample B as its sample is more disperse

Sample A as it has the smaller sample

Sample A as its sample is more disperse

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Question 10

2pts

Why might a company use a higher confidence interval, such as 99%, rather than a lower confidence interval, such as 80%?

Group of answer choices

They make computer parts where they are too small for higher accuracy

They track the migration of fish where accuracy is not as important

They make children's toys where precision is expected

They are in the medical field, where accuracy is important

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Question 11

2pts

Determine the minimum sample size required when you want to be 95% confident that the sample mean is within two units of the population mean. Assume a population standard deviation of 4.3 in a normally distributed population.

Group of answer choices

16

22

18

20

Question 12

2pts

Determine the minimum sample size required when you want to be 99% confident that the sample mean is within 0.50 units of the population mean. Assume a population standard deviation of 1.4 in a normally distributed population.

Group of answer choices

30

31

52

53

Question 13

2pts

In a sample of 14 CEOs, they spent an average of 12.9 hours each week looking into new product opportunities with a sample standard deviation of 4.9 hours. Find the 95% confidence interval. Assume the times are normally distributed.

Group of answer choices

(9.9, 15.9)

(10.1, 15.7)

(8.0, 17.8)

(10.3, 15.5)

Question 14

2pts

In a sample of 12 kids, their mean time on the internet on the phone was 3.9 hours with a sample standard deviation of 0.7 hours. Which distribution would be most appropriate to use?

Group of answer choices

t distribution as the data are assumed to be normally distributed

t distribution as the population is not normally distributed

z distribution as the standard deviation always represents the population

Neither z nor t, as the population is not known to be normally distributed and there is a small sample

Question 15

2pts

Under a time crunch, you only have time to take a sample of 15 water bottles and measure their contents. The sample had a mean of 20.05 ounces with a sample standard deviation of 0.3 ounces. What would be the 90% confidence interval, when we assumed these measurements are normally distributed?

Group of answer choices

(19.88, 20.22)

(19.75, 20.35)

(19.91, 20.19)

(19.92, 20.18)

Question 16

2pts

Say that a supplier claims they are 99% confident that their products will be in the interval of 50.02 to 50.38. You take samples and find that the 99% confidence interval of what they are sending is 50.01 to 50.39. What conclusion can be made?

Group of answer choices

The supplier is more accurate than they claimed

The supplier products have a higher mean than claimed

The supplier is less accurate than they claimed

The supplier products have a lower mean than claimed

Question 17

2pts

Market research indicates that a new product has the potential to make the company an additional $1.6 million, with a standard deviation of $2.5 million. If these estimates were based on a sample of 8 customers from a normally distributed data set, what would be the 95% confidence interval?

Group of answer choices

(-0.09, 4.10)

(-0.13, 3.33)

(-0.49, 3.69)

(0.00, 3.69)

Question 18

2pts

In a sample of 28 cups of coffee at the local coffee shop, the temperatures were normally distributed with a mean of 182.5 degrees with a sample standard deviation of 14.1 degrees. What would be the 95% confidence interval for the temperature of your cup of coffee?

Group of answer choices

(177.28, 187.72)

(148.40, 176.60)

(177.03, 187.97)

(168.40, 196.60)

Question 19

2pts

In a situation where the sample size from a normally distributed data set was decreased from 45 to 22, what would be the impact on the confidence interval?

Group of answer choices

It would become wider due to using the t distribution

It would become narrower with fewer values

It would become narrower due to using the z distribution

It would remain the same as sample size does not impact confidence intervals

Question 20

2pts

You needed a supplier that could provide parts as close to 76.8 inches in length as possible. You receive four contracts, each with a promised level of accuracy in the parts supplied. Which of these four would you be most likely to accept?

Group of answer choices

Mean of 76.800 with a 99% confidence interval of 76.5 to 77.1

Mean of 76.800 with a 90% confidence interval of 76.6 to 77.0

Mean of 76.8 with a 99% confidence interval of 76.6 to 77.0

Mean of 76.8 with a 95% confidence interval of 76.6 to 77.0