Using the 2" 2 n rule, determine the number of classes needed for the following data set sizes. a) n= 50 b) n= 400 c) n = 1500 d) n= 2000 a) The number of classes needed when n = 50 is b) The number of classes needed when n = 400 is c) The number of classes needed when n = 1500 is d) The number of classes needed when n = 2000 is