Suppose the average speeds of passenger trains traveling fromNewark, New Jersey, to Philadelphia, Pennsylvania, are normallydistributed, with a mean average speed of 88 miles per hour and astandard deviation of 6.4 miles per hour.
(a) What is the probability that a train will average less than72 miles per hour?
(b) What is the probability that a train will average more than80 miles per hour?
(c) What is the probability that a train will average between 91and 99 miles per hour?
(Round the values of z to 2 decimal places. Round your answersto 4 decimal places.)
(a) P(x < 72)=???
(b) P(x > 80)=???
(c) P(91 ≤ x ≤ 99)=???
