The travel time for a college student traveling between her home and her college is uniformly distributed between 40 and 90 minutes. The probability that she will finish her trip in 60 minutes or less is
A) 0.8.
B) 0.4.
C) 0.2.
D) 1.00.

Question

Quizplus · Accepted Answer

Since the travel time is uniformly distributed between 40 and 90 minutes, the probability of finishing the trip in 60 minutes or less is equal to the ratio of the length of the interval from 40 to 60 minutes to the length of the entire interval from 40 to 90 minutes.

The length of the interval from 40 to 60 minutes is 20, and the length of the entire interval from 40 to 90 minutes is 50. Therefore, the probability of finishing the trip in 60 minutes or less is 20/50, which simplifies to 2/5 or 0.4.

Hence, the best choice is B.

The Travel Time for a College Student Traveling Between Her