Answer
a)The event is very unlikely and probably not the husband is the father.
b)240 days
Work Step by Step
a)$z=\frac{value-mean}{standard \ deviation}=\frac{308-268}{15}=2.67$.
By using the table the corresponding probability: 1-0.9962=0.0038, which is very low, hence the event is very unlikely and probably not the husband is the father.
b)By using the table, the z-score corresponding to 0.03: z=-1.88. Hence the correspondig value:$mean+z\cdot standard \ deviation=268-1.88\cdot 15=239.8\approx240.$
