Question

You want to estimate the mean salary of people in a country, so you take a random sample of 121 people from around the country. The sample had an average salary of 845000 dollars with population standard deviation of 500.00 dollars. Calculate the Upper Limit of the 5% confidence interval for the mean salary of the people in the country Reminder: You only need to calculate the Upper Limit of the confidence interval.

Answer 1

Given,

n= 121

$\mu$= 8450

$\sigma$= 500

Now calculate 90% of confidence interval

CI = x_bar $\pm$ z*($\sigma$/$\sqrt$n)

​​​​​​z value for 90% confidence interval is 1.645.

CI = 8450 $\pm$ 1.645*(500/$\sqrt$121)

= 8450 $\pm$ 74.773

Therefore 90% of confidence interval is

CI = 8450-74.773 and CI) 8450 + 74.773

= 8375.227 and CI = 8524.773

Hence 90% of confidence interval is (8375.227,8524.773).