4 The heights, in metres, of white pine trees are normally distributed with mean 19.8 and standard deviation 2.4 .
In a certain forest there are 450 white pine trees.
- How many of these trees would you expect to have height less than 18.2 metres?
The heights, in metres, of red pine trees are normally distributed with mean 23.4 and standard deviation \(\sigma\). It is known that \(26 \%\) of red pine trees have height greater than 25.5 metres. - Find the value of \(\sigma\).