A department store is running a promotion one Saturday by givingout coupons for

A department store is running a promotion one Saturday by givingout coupons for $10 of free merchandise. Based on the datacollected in the past only one-fourth of customers who shop onthat Saturday use the coupon but do not purchase any othermerchandise. However one-third of customers spend $40 andone-third spend $75. The remainder of customers who come in thestore do not take advantage of the promotion at all.