i need solution for this question.

A consumer agency that proposes that lawyer's rate are too high wanted to estimate the mean hourly rate for all lawyers in New york is 110(usd).

a)construct %97 confidence interval for the mean hourly charges for all lawyers in New york.

b)explain why we need to make confidence interval.why can we not say that the mean hourly rate for all lawyers in New york is 420(usd)?

thanks for everything.