A store has a box of coupons at the entrance. There are 600 20% coupons; 250 30% coupons; and 150 50% coupons. Each customer entering the store gets to pick a coupon from the box. Let n represent the percent value of the discount coupon. a. Find the probability that a customer picks a 30% discount coupon. Enter as a decimal rounded to TWO places. b. What is E(n )