You are interested in the average amount of money Queen's students made during the summer. Assume the population mean is μ and variance σ2. You don't want to ask everyone in the population (all Queen's students), so you decide to randomly ask 5 people. Denote their summer income as Y1,Y2,Y3,Y4, and Y5. Consider an estimator W1 which is equal to the sample average income, 51(Y1+Y2+Y3+Y4+Y5). What are the expected value and variance of W1 in terms of μ and σ2 ? Is the estimator unbiased estimator of the population mean?