Sample Simple Will Estimating Population Mean In Simple Random Sample?

Estimating population mean in simple random sample? - sample simple will

I do not know how to solve this problem, any help is good

Accountant wants to estimate the average time to complete the declaration TAC 200 customers. A simple random sample was selected from 20 clients and the time to complete their tax returns measured. The meter calculates the sample average = 2.1 hours and standard deviation = 0.4 hours. The estimate of the population mean.