In: Statistics and Probability
a) On the throw of a fair die, the expected value of the number showing is 3.5 and the standard deviation is 1.71. What is the expected value and standard deviation of the sum of the values from the throw of a pair of dice
b) Suppose Y1 and Y2 are independent, Var(Y1) = Var(Y2) = σy2 and Z1 = Y1+Y2 .What is Var(Z1)? How does this compare to the result found in part a)?
c) Generalize the previous results. Suppose Y1, Y2, · · · , Yn are independent, Var(Y1) = Var(Y2) = · · · = Var(Yn) = σ2y and Z2 = Y1 + Y2 + · · · + Yn. What is Var(Z2)?
d) Again, let’s keep generalizing these results. Suppose Y1, Y2, · · · , Yn are independent, Var(Y1) = Var(Y2) = · · · = Var(Yn) = σ2y and Z3 = 1/n (Y1 + Y2 + · · · + Yn). What is Var(Z3)?