The extent to which a distribution is peaked or flat, also called the kurtosis of the distribution, is often measured by means of the quantity α4 = µ4/σ4 Use the formula for µ4 obtained in Exercise 4.25 to find α4 for each of the following symmetrical distributions, of which the first is more peaked (narrow humped) than the second:
(a) f (- 3) = 0.06, f (- 2) = 0.09, f (- 1) = 0.10, f (0) = 0.50, f (1) = 0.10, f (2) = 0.09, and f (3) = 0.06;
(b) f (- 3) = 0.04, f (- 2) = 0.11, f (- 1) = 0.20, f (0) = 0.30, f (1) = 0.20, f (2) = 0.11, and f (3) = 0.04.