In a random sample of 60 computers, the mean repair cost was $150. Assume the population standard deviation is $36. Construct a 90% confidence interval for the population mean.
Accepted Solution
A:
Answer: 90% confidence interval for the population mean is [tex]149.01,\ 150.99[/tex]Step-by-step explanation:Given that, in a random sample of 60 computers, the mean repair cost was $150, with the population standard deviation is $36. Here,[tex]n=60,\mu=150,\sigma=36[/tex]In case of 90% confidence interval, [tex]Z=1.645[/tex]We know that, the confidence interval will be,[tex]=\mu\pm Z\dfrac{\sigma}{n}[/tex]Putting all the values,[tex]=150\pm 1.645\times \dfrac{36}{60}[/tex][tex]=150\pm 0.987[/tex][tex]=149.01,\ 150.99[/tex]