I purchase x movie tickets y candy bars and z fountain drinks if each movie cost $11.50 each candy bar costs $2.25 and each fountain drink costs $4.75 write a equation for the total cost t in the terms of x, y, and z

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%