Question

Question 1

Suppose you needed to form a 92% confidence interval for a population mean. What z value would you use?

A.

1.41

B.

.82

C.

1.96

D.

1.75

Question 2

Which of the following is a way to INCREASE the width of a confidence interval?

A.

increase the chance for error

B.

increase the confidence level

C.

decrease the error

D.

increase the sample size

Question 3

In a random sample of 60 computers, the mean repair cost was $150 with a standard deviation of $36. Construct a 99% confidence interval for the population mean. DON'T JUST GIVE THE ANSWER - SHOW WORK AND EXPLAIN YOUR PROCESS EACH STEP OF THE WAY SO THAT I CAN FOLLOW WHAT YOU DID AND CHECK YOUR WORK.

Question 4

In order to efficiently bid on a contract, a contractor wants to be 95% confident that his error is less than two hours in estimating the average time it takes to install tile flooring. Previous contracts indicate that the standard deviation is 4.5 hours. How large a sample must be selected? DON'T JUST GIVE THE ANSWER - SHOW WORK AND EXPLAIN YOUR PROCESS EACH STEP OF THE WAY SO THAT I CAN FOLLOW WHAT YOU DID AND CHECK YOUR WORK.

Question 5

A simple random sample of 25 is drawn from a population that is normally distributed. The sample mean is found to be 108 with a sample standard deviation, s is 10 ( population standard deviation is unknown). Construct the 95% confidence interval.

A.

4.13

B.

103.87-112.13

C.

3.92

D.

104.08 - 111.92

Question 6

When 500 college students were surveyed, 30% said that they own their car. Construct a 95% confidence interval for the proportion of college students who say they own their cars. DON'T JUST GIVE THE ANSWER - SHOW WORK AND EXPLAIN YOUR PROCESS EACH STEP OF THE WAY SO THAT I CAN FOLLOW WHAT YOU DID AND CHECK YOUR WORK.

Question 7

A survey of 2070 golfers showed that 347 of them are left-handed. What sample proportion would be used to find a confidence interval for the population proportion?

A.

.832

B.

.210

C.

.144

D.

.168

Question 8

A private opinion poll is conducted for a politician to determine what proportion of the population favors decriminalizing marijuana possession. How large a sample is needed to be 95% confident that the sample proportion will not differ from the true proportion by more than 6%? DON'T JUST GIVE THE ANSWER - SHOW WORK AND EXPLAIN YOUR PROCESS EACH STEP OF THE WAY SO THAT I CAN FOLLOW WHAT YOU DID AND CHECK YOUR WORK. (Hint: you need to use the formula to determine "n", also p/q hat were not given so what must you use?).

Question 9

A car maker claims that its new sub-compact car gets better than 49 miles per gallon on the highway. Write the null and alternative hypotheses.

Question 10

The mean age of bus drivers in Chicago is 50.1 years. If a hypothesis test is performed, how should you interpret a decision that rejects the null hypothesis?

	A.	There is sufficient evidence to reject the claim that μ=50.1
	B.	There is not sufficient evidence to support the claim that μ=50.1
	C.	There is sufficient evidence to support the claim that μ=50.1
	D.	There is not sufficient evidence to reject the claim that μ=50.1

Answer 1