Police recorded the average speed of cars driving on a busy street by a school. for a sample of 2525 ​speeds, it was determined that the average amount over the speed limit for the 2525 speeds was 1

Police recorded the average speed of cars driving on a busy street by a school. for a sample of 2525 ​speeds, it was determined that the average amount over the speed limit for the 2525 speeds was 10.110.1 mph with a standard deviation of 77 mph. the 9595​% confidence interval estimate for this sample is 7.217.21 mph to 12.9912.99 mph. ​a) what is the margin of error for this​ problem? ​b) what size sample is needed to reduce the margin of error to no more than plus or minus±11​?