Question

A machine has two components both of which have a lifespan, in months, that is exponentially distributed with mean 8. The lifespan of the two components are independent. Find the probability both components are functioning in 12 months.

Answer 1

0.0498

Explanation:

In this question,

x~exponential

we have

mean = 1/λ = 8

from here we cross multiply, when we do

such that

λ = 1/8

probability of x functioning in 8 months

= e^-λx

= e^-1/8x12

= e^-1.5

= 0.2231

i got this value through the use of a scientific calculator

then the probability that these two are greater than 12

= 0.2231²

= 0.04977

= approximately 0.0498

therefore the probability that both components are functioning in 12 months is 0.0498