4 The time taken for cucumber seeds to germinate under certain conditions has a normal distribution with mean 125 hours and standard deviation \(\sigma\) hours.
- It is found that \(13 \%\) of seeds take longer than 136 hours to germinate. Find the value of \(\sigma\).
- 170 seeds are sown. Find the expected number of seeds which take between 131 and 141 hours to germinate.