1.A 95% confidence interval for the average amount spent on textbooks by undergraduate students at a large state university per semester is $400 +/- $50. Would it be correct to state that the true population average could be $360?

A)Yes

B)No

2.A consumer testing organization is comparing the battery life of two different models of PCs.They randomly sample 49 of each model of PC (independent samples).The 49 PCs in group 1 have an average battery life of 11 hours with a sample standard deviation of 0.7 hours.The 49 PCs in group 2 have an average battery life of 9 hours with a sample standard deviation of 1.4 hours

The standard error for the difference in the two averages is:

A)0.7 + 1.4 = 2.1 hours

B)(0.7^2 + 1.4^2) = 1.56 hours

C)(0.1^2 + 0.2^2) = 0.223 hours

D)0.1 + 0.2 = 0.3 hours

3.A consumer testing organization is comparing the battery life of two different models of PCs.They randomly sample 49 of each model of PC.The 49 PCs in group 1 have an average battery life of 11 hours with a sample standard deviation of 0.7 hours.The 49 PCs in group 2 have an average battery life of 9 hours with a sample standard deviation of 1.4 hours.

The 95% confidence interval of the difference between the two group population means is:

A)(11-9) +/- 2 * 0.223 = 2 +/- 0.446 hours

B)(11-9) +/- 1 * 0.223 = 2 +/- 0.223 hours

C)(11-9) +/- 2 * 1.56 = 2 +/- 3.12 hours

D)(11-9) +/- 3 * 0.223 = 2 +/- 0.669 hours

4.For large random samples, when we look at sample means or proportions ... What happens to the width of a confidence interval when the confidence level is increased from 68% to 95% (holding all else constant)? Explain briefly.

5.We randomly select 1000 adults from a population of 2 million and also randomly select 1000 adults from a population of 20 million. If the sample standard deviations are the same, how will the margins of error compare for 95% confidence intervals for the true population average? Will the margin of error for the sample from the larger population be greater than, the same, or less than the margin of error for the sample from the smaller population? Explain briefly.