A consumer agency that proposes that lawyers rates are too high wanted to estimate the mean hourly

Question:

A consumer agency that proposes that lawyers’ rates are too high wanted to estimate the mean hourly rate for all lawyers in New York City. A sample of 70 lawyers taken from New York City showed that the mean hourly rate charged by them is $570. The population standard deviation of hourly charges for all lawyers in New York City is $110.
a. Construct a 99% confidence interval for the mean hourly charges for all lawyers in New York City.
b. Suppose the confidence interval obtained in part a is too wide. How can the width of this interval be reduced? Discuss all possible alternatives. Which alternative is the best?