Question 14 of 14

Find the sample size needed to estimate the mean age of movie patrons such that it can be sold with 90% confidence that the sample mean Is within 2.5 years of the

population mean. Assume that a = 19.5 years, based on a previous report. Should the sample be obtained from one movie at one theater?

The required sample size is ____. (Round up to the nearest integer.)

 

Should the sample be obtained from one movie at one theater?

A. The sample should not be obtained from one movie at one theater, because that sample could be easily biased. Instead, a stratified sample of the broader population should be obtained.

B. The sample should not be obtained from one movie at one theater, because that sample could be easily blased. Instead, a simple random sample of the broader

population should be obtained.

C. The sample should be obtained from one movie at one theater, because that sample is representative of the population.

D. The sample should not be obtained from one movie at one theater, because that sample could be easily biased. Instead, a cluster sample of the broader population should be obtained.

a simple random sample of 60 items resulted in a sample mean of 80. The population standard deviation is  15.

1. Compute the 95% confidence interval for the population mean.

2. Assume that the same sample mean was obtained from a sample of 120 items. Provide

   a 95% confidence interval for the population mean.

3. What is the effect of a larger sample size on the interval estimate?

A simple random sample of size n is drawn from a population that is known to be normally distributed. The sample mean, x¯\bar{x}xˉ, is determined to be 104.3 and the sample standard deviation, s, is determined to be 15.9. (a) Construct the 90% confidence interval for the population mean if the sample size, n, is 15. (b) Construct the 90% confidence interval for the population mean if the sample size, n, is 25. How does increasing the sample size affect the width of the interval? (c) Construct the 95% confidence interval for the population mean if the sample size, n, is 15. Compare the results to those obtained in part (a). How does increasing the level of confidence affect the confidence interval? (d) Construct the 90% confidence interval for the population standard deviation if the sample size, n, is 15.�