CAIE FP2 2010 June — Question 8

Exam BoardCAIE
ModuleFP2 (Further Pure Mathematics 2)
Year2010
SessionJune
TopicExponential Distribution
TypeMultiple independent components

8 A certain mechanical component has a lifetime, \(T\) months, which has a negative exponential distribution with mean 2.5.
  1. A machine is fitted with 5 of these components which function independently.
    1. Find the probability that all 5 components are operating 3 months after being fitted.
    2. Find also the probability that exactly two components fail within one month of being fitted.
  2. Show that the probability that \(n\) independent components are all operating \(c\) months after being fitted is equal to the probability that a single component is operating \(n c\) months after being fitted.