Finding and Interpreting the expected value for the selling price

Question

A store is having a special promotion an a radio that regularly costs $30.00. A customer purchasing the radio draws a discount coupon at random out of a box and then puts it back. In the box there are 8 coupons for $4.00 off the regular price, five coupons for $7.00 off the regular price, and two coupons for $12.00 off the regular price. Each customer pays the regular cost minus the discounted amount on the coupon drawn. Find the expected value for the selling price and interpret

Answer 1

15 coupons

8 for $4 off

5 for $7 off

2 for $12 off

regular $30 price

with a randomly selected coupon what is the expected price??

8(4)/15+5(7)/15+2(12)/15= (32+35+24)/15= 91/15= 6 1/15= $6.07 off

expected discounted price= 30-6.07

=$23.93