SOA Exam P Sample Question 142

Study guide: Exam P-1

The lifespan, in years, of a certain computer is exponentially distributed. The probability that its lifespan exceeds four years is 0.30.

Let $f(x)$ represent the density function of the computer's lifespan, in years, for $x > 0$ .

Determine which of the following is an expression for $f(x)$ .

A) $1 - (0.3)^{-x/4}$
B) $1 - (0.7)^{x/4}$
C) $1 - (0.3)^{x/4}$
D) $-\frac{\ln 0.7}{4}(0.7)^{x/4}$
E) $-\frac{\ln 0.3}{4}(0.3)^{x/4}$

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