3) A department store is running a promotion one Saturday by giving out coupons for $10 of free merchandise. Based on date collected in the past, only % of customers who shop on that Saturday use the coupon, but do not purchase any other merchandise. However, 1/3 of customers purchase $40 in merchandise and then use the coupon. Another 1/3 of customers use the coupon after ringing up a total of $75 in merchandise. The remainder of customers who come in the store do not take advantage of the promotion at all. a) Find the expected value of the promotion per customer for the department store.

b) If the store has 720 customers on the promotional Saturday, what is the expected revenue for the day?​