4-33. Suppose that the lifetime (in hours) of a particular piece of electrical equipment can be characterized by the probability density function f (x) = - 1 200 e−x/200, x > 0;

0 elsewhere.

Verify that the average life of this electrical component is 200 hours.

Suppose that an event A is defined as “the component fails in 60 or fewer hours.” Find P(A).