Probability Questions:

24. Shadia has invented a game for one person. She throws two dice repeatedly until the sum of the two numbers shown is either six or eight. If the sum is six, she wins. If the sum is eight, she loses. If the sum is any other number, she continues to throw until the sum is six or eight.

(b) What is the probability that a second throw is needed?

(c) Find an expression for the probability that Shadia wins on her first, second or third throw.

(d) Calculate the probability that Shadia wins the game.

28. There are two white and three black discs in a bag. Two players A and B are playing a game in which they draw a disc alternately from the bag and then replace it. Player A must draw a white disc to win and player B must draw a black disc. Player A goes first. Find the probability that:

(d) player A wins the game

Answers:

24 (b) 13/18 (c) 5/36 + 13/18 5/36 + 5/36 (d)

28 (d) 10/19