4 The marks, \(x\), of a random sample of 50 students in a test were summarised as follows.
$$n = 50 \quad \Sigma x = 1508 \quad \Sigma x ^ { 2 } = 51825$$
- Calculate unbiased estimates of the population mean and variance.
- Each student's mark is scaled using the formula \(y = 1.5 x + 10\). Find estimates of the population mean and variance of the scaled marks, \(y\).