Statistics
posted by Anonymous on .
This is a stats problem.
Twenty percent of all trucks undergoing a certain inspection will fail the inspection. Assume that trucks are independently undergoing this inspection, one at a time. The expected number of trucks inspected before a truck fails inspection is...?
I belive this is a geometric probability problem, but I don't know how to solve it. Please help.

This is a geometric probability problem. (Chapter 5)
P = 0.20
E(X) = 1/p = 1/0.2 = 5 trucks