# Math Help - Exponential distribution

1. ## Exponential distribution

The time it takes to complete a service call to a mail-order computer company has exponential distribution with an average of 4 minutes, i.e., λ = 1/4 min-1. Within what time will 90% of the calls be completed?

2. Originally Posted by aaronrj
The time it takes to complete a service call to a mail-order computer company has exponential distribution with an average of 4 minutes, i.e., λ = 1/4 min-1. Within what time will 90% of the calls be completed?
Solve for a: $\int_0^a f(t) \, dt = 0.9$.