Jack Hall is home to the Math Department. In 140 trips on the Jack Hall elevator, the average waiting time for the car to arrive was 6 minutes. The largest number of trips (among those 140) in which it took 12 minutes or longer for the car to arrive is _______. Solution exponential with lambda = 1/ 6 . P(X > =12) = 1 - (1 - e^(-12 /6)) = e^-2 = 0.135 number of trips = 140*P(X >=12) = 140 * 0.135~ 19.

1. Jack Hall is home to the Math Department. In 140 trips on the Jack Hall elevator, the average
waiting time for the car to arrive was 6 minutes. The largest number of trips (among those 140)
in which it took 12 minutes or longer for the car to arrive is _______.
Solution
exponential with lambda = 1/ 6 .
P(X > =12) = 1 - (1 - e^(-12 /6)) = e^-2 = 0.135
number of trips = 140*P(X >=12) = 140 * 0.135~ 19