Answer:

Explanation:
An uniform probability is a case of probability in which each outcome is equally as likely.
For this situation, we have a lower limit of the distribution that we call a and an upper limit that we call b.
The probability density function of the uniform distribution is:

Uniformly distributed and that the required time ranges between 45 minutes to 11/2hours.
Each hour has 60 minutes, so 1 and a half hours is 90 minutes.
So

The probability density function is:

