6 A random sample of 9 members is taken from the large number of members of a sports club, and their heights are measured. The heights of all the members of the club are assumed to be normally distributed. A 95\% confidence interval for the population mean height, \(\mu\) metres, is calculated from the data as \(1.65 \leqslant \mu \leqslant 1.85\).
- Find an unbiased estimate for the population variance.
- Denoting the height of a member of the club by \(x\) metres, find \(\Sigma x ^ { 2 }\) for this sample of 9 members.