Tickets numbered 1 to 20 are mixed up together and then a ticket is drawn at random. What is the probability that the ticket has a number which is a multiple of 3 or 7?

9 A card is drawn from an ordinary pack and a gambler bets that it is a spade or an ace. What are the odds against his winning this bet? 10 17 cards numbered 1, 2, 3, ..., 16, 17 are put into a box and mixed thoroughly. One person draws a card from the box. Find the probability that the number on the card is a prime. 12 Two dice are thrown. What is the probability of obtaining a total of 10 or 11? 13 Find the probability of choosing square numbers between 2 and 100.