Ch 10 - Probability

It is estimated that 92% of students in Australia own a mobile phone. Two students are chosen at random. What is the probability that neither of them owns a mobile phone?

• 0.16

• 0.08

• 0.0064

• 0.064

Two ordinary dice are rolled. The score is the sum of the numbers on the top faces. What is the probability that the score is 9?

A chessboard has 32 black squares and 32 white squares. Amy chooses three different squares at random. What is the probability that the three squares Amy chooses are the same colour?

• 1/8

John has four pairs of socks in a drawer, each pair a different colour. He selects socks one at a time at random from the drawer. What is the probability that he does not have a matching pair after selecting the fourth sock?

Four candidates A, B, C and D are standing for election as class captain. Their names are written on four pieces of paper that are placed in a container and drawn out randomly to determine their positions on the ballot paper. What is the probability that the order of the names on the ballot paper is the order shown in the diagram?

Four green and two blue balls are placed in a bag. One ball is selected at random, removed and replaced by a ball of the other colour. The bag is then shaken and a second ball is randomly selected. What is the probability that the second ball selected is blue?

A set of four cards contains a jack, a queen and two kings. Henry selects one card and then, without replacing it, selects another. What is the probability that at least one of Henry’s cards is a king?

How many times would you need to roll a die so that the probability of rolling at least one five was greater than 83%?

• 9

• 10

• 11

• 12

In a group of 50 Year 12 students there are 27 who study Chemistry, 21 who study Physics and 8 who study both sciences. What is the probability that a student chosen at random does not study either Chemistry or Physics?

A die with twelve faces has the numbers from 1 to 12 on its faces. (It is in the shape of a regular polyhedron, so that when it is rolled, each number has the same probability of appearing on the uppermost face.) If it is rolled three times, what is the probability that the number 10 appears on the uppermost face exactly twice?