Question

A random sample of the closing stock prices in dollars for a company in a recent year is listed below. Assume that sigma is ​$2.29. Construct the 90​% and 99​% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals.

18.16 17.37 20.79 21.54 16.89 19.22 22.91 18.71 15.42 15.21 20.67 20.85 18.53 22.85 18.47 17.13

The​ 90% confidence interval is left parenthesis $ nothing comma $ nothing right parenthesis . ​(Round to two decimal places as​ needed.)

The​ 99% confidence interval is left parenthesis $ nothing comma $ nothing right parenthesis . ​(Round to two decimal places as​ needed.)

Which statement below interprets the results​ correctly?

The probability that the mean closing stock price is in the​ 90% confidence interval is about​ 90% and the probability that the mean closing stock price is in the​ 99% confidence interval is about​ 99%.

The​ 90% confidence interval contains the mean closing stock price​ 90% of the time and the​ 99% confidence interval contains the mean closing stock price​ 99% of the time.

There is​ 90% confidence that the mean closing stock price is in the​ 90% confidence interval and​ 99% confidence that the mean closing stock price is in the​ 99% confidence interval. ​

90% of the mean closing stock prices are in the​ 90% confidence interval and​ 99% of the mean closing stock prices are in the​ 99% confidence interval.

Which interval is​ wider?

The​ 99% confidence interval

The​ 90% confidence interval

Answer 1