In: Statistics and Probability
An economist wants to estimate the mean per capita income (in thousands of dollars) for a major city in California. Suppose that the mean income is found to be $22.6$ for a random sample of 2692 people. Assume the population standard deviation is known to be $12.4$. Construct the 98% confidence interval for the mean per capita income in thousands of dollars. Round your answers to one decimal place.
Given that,
= 22.6
= 12.4
n =2692
At 98% confidence level the z is ,
= 1 - 98% = 1 - 0.98= 0.02
/ 2 = 0.02/ 2 = 0.01
Z/2 = Z0.01= 2.326
Margin of error = E = Z/2* ( /n)
=2.326 * (12.4 / 2692)
= 0.6
At 98% confidence interval estimate of the population mean is,
- E < < + E
22.6 - 0.6 < < 22.6 + 0.6
22.0< < 23.2
(22.0,23.2 )