3 A random sample of 150 students attending a college is taken, and their travel times, \(t\) minutes, are measured. The data are summarised by \(\Sigma t = 4080\) and \(\Sigma t ^ { 2 } = 159252\).
- Calculate unbiased estimates of the population mean and variance.
- Calculate a \(94 \%\) confidence interval for the population mean travel time.