To determine the effect their salespeople have on purchases, a department store polled 700 shoppers regarding whether or not they made a purchase and whether or not they were pleased with the service they received. Of those who made a purchase, 151 were happy with the service and 153 were not. Of those who made no purchase, 221 were happy with the service and 175 were not. Use probability rules (when appropriate) to find the probability of the event stated. (Enter your answers as fractions.)

(a) A shopper was happy with the service received. (b) A shopper was unhappy with the service received.