Question

A website advertises job openings on its website, but job seekers have to pay to access the list of job openings. The website recently completed a survey to estimate the number of days it takes to find a new job using its service. It took the last 31 customers an average of 80 days to find a job. Assume the population standard deviation is 10 days. Construct a 95% confidence interval of the population mean number of days it takes to find a job.

Answer 1

Solution :

Given that,

Sample size = n = 31

Z/2 =Z0.025 = 1.96

Margin of error = E = Z/2* ( /n)

= 1.96* (10 / 31)

Margin of error = E = 3.5

At 95% confidence interval estimate of the population mean is,

- E < < + E

80 - 3.5 < < 80 + 3.5

76.5 < < 83.5

( 76.5,83.5 )