Ace! professional tennis player rafael nadal hits the ball extremely hard. his first-serve speeds follow a normal distribution with mean 115 miles per hour (mph) and standard deviation 6 mph. choose one of nadal’s first serves at random. let y = its speed, measured in miles per hour. find p(y > 121) and interpret the result. what is p(y ≥ 121)? explain. find the value of c such that p(y ≤ c) = 0.15. show your work