Professional tennis player Novak Djokovic hits the ball extremely hard. His first-serve

speeds follow a normal distribution with

mean 112 miles per hour (mph) and

standard deviation 6 mph. Choose one of

Djokovic's first serves at random. Let Y= its

speed, measured in miles per hour.

a. A first serve with a speed less than 100

miles per hour is considered "slow." What

percent of Djokovic's first serves are slow?

b. Calculate A120 < Y<125) and interpret the

result.

C. Find the 15th percentile of Novak

Djokovic's firstserve speed distribution.