Question no 2

Morgan has a mobile phone of this model. Suppose that at some time when the mobile phone is quite old, Morgan gives the phone to their younger sibling Ellis. (c) Obtain the p.d.f. of the total lifetime of the component in the mobile phone when Morgan gives the phone to Ellis, and hence find the expected total lifetime of this component. [4] (d) Calculate the probability that Ellis will not have to replace the component for at least one year after being given the phone. (4] Explain why the expected total lifetime of the component in the phone when Morgan gives the phone to Ellis is longer than the expected total lifetime of a new component chosen at random and fitted in the phone. [2]