Solution
Given a normally distributed lifespan:
Mean = 12.4 yrs
Standard deviation =1.9yrs
x = 17yrs
[tex]\begin{gathered} Z=\frac{x-\mu}{\sigma} \\ Z=\frac{17-12.4}{1.9} \\ Z=\frac{4.6}{1.9} \\ Z=2.421 \end{gathered}[/tex][tex]P(x>Z)=0.0077[/tex]
Hence the probability that it will last longer = 0.0077
