1 Leaves from a certain type of tree have lengths that are distributed with standard deviation 3.2 cm . A random sample of 250 of these leaves is taken and the mean length of this sample is found to be 12.5 cm .
- Calculate a \(99 \%\) confidence interval for the population mean length.
- Write down the probability that the whole of a \(99 \%\) confidence interval will lie below the population mean.