Question

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

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