Prob. 3: Stats/GHWS Page 2 of 3 (61\") 3. Annual incomes for heads of household in a section of a city have approximately a gamma distribution with a = 20 and ,3 = 1000. Round values to the nearest cent when necessary. (a) (3 pts} Find the mean, variance and standard deviation of these incomes. (b) (3 pts) Would you expect to nd many incomes in excess of $30,000 in this section of the city? [Hint Think about how many standard deviation units this value is from the mean. Often items beyond 2 standard deviations from the mean are considered unusual! A quick way to see how many standard deviation units a value is from the mean is to use the z-score formula: z z (y polo-J Bonus points are availabie ifyou can nd the P(Y )- 30, 000). You can use any means necessary for this as I do not recommend doing it by hand. but you must show me the set-up of your integral