Exponential Distribution

ok so my problem is:

An outbreak of a particular type of timber infestation occurs, on average, every 30 years for a given region. assuming the probability of an infestation follows an exponential probability distribution, what is the probability of two infestation occurring within 6 years of each other?

I think that i am supposed to use the excel formula =expondist but i cant seem to get it to cooperate. anyone have any input?


TS Contributor
Two infestations occur with 6 years of eachother if the waiting time to the next is less than 6 years.