I need the solution to this question.

The indoor pool at the local YMCA uses a filtration system to keep the pool water clean. Thissystem requires that the filter be backwashed when the discharge pressure for the water pumpreaches 25 psi. The average time between backwashing is 10.0 days and this time period followsthe exponential probability distribution. What is the probability that the next backwash will occurbetween 6 and 9 days after the prior backwash?

Thank You