1. Problem11.17Thehypergeometricdistribution describes the probability mass function of the number of red balls drawn when n balls are randomly chosen from an urn containing R red and W white balls. Show that the variance of the number of red balls drawn is given by n R R+W

(1 − R R+W

)R+W−n R+W−1

. Hint: the number of red balls drawn can be written as X1 + ...+ XR, where Xi equals 1iftheith red ball is selected and 0 otherwise.