The base parking charge at a mall on a sunday is $2 per hour. if a vehicle is parked for 4 hours, only $6 is charged. what percentage is saved on the base charge for a vehicle parked for 4 hours? a 10% b 20% c 25% d 30% e 50%

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%