A petrol station runs a promotion to advertise its new car wash. Each customer is given a pair of cards, each with a letter printed on it. there are a large number of different cards - each one has one of the symbols W, A, $ or H on it. Only 10% of the cards have a $ symbol, and the other three cards are equally likely. If the two cards are both the same the customer wins a prize.
(a) What is the probability that a customer is given a W card and a H card?
(b) What is the probability that a customer wins a prize?