Question

This is a question I need help on for homework

Answer 1

Given a normally distributed lifespan:

Mean = 12.4 yrs

Standard deviation =1.9yrs

x = 17yrs

`\begin{gathered} Z=(x-\mu)/(\sigma) \\ Z=(17-12.4)/(1.9) \\ Z=(4.6)/(1.9) \\ Z=2.421 \end{gathered}`
`P(x>Z)=0.0077`

Hence the probability that it will last longer = 0.0077