Question

you are given the sample mean and the population standard deviation. use this information to construct the 90% and 95% confidence intervals for the population mean. interpret the results and compare the widths of the confidence intervals.
from a random sample of 47 business days, the mean closing price of a certain stock was $116.50. assume the population standard deviation is $9.71.
the 90% confidence interval is (114.17, 118.83).
(round to two decimal places as needed.)
the 95% confidence interval is (113.72, 119.28).
(round to two decimal places as needed.)
which interval is wider? choose the correct answer below.
the 90% confidence interval
the 95% confidence interval

Explanation:

Step1: Calculate the width of 90% confidence interval

Width = Upper limit - Lower limit = \(118.83 - 114.17=4.66\)

Step2: Calculate the width of 95% confidence interval

Width = Upper limit - Lower limit = \(119.28 - 113.72 = 5.56\)

Answer:

The 95% confidence interval