Unit E: Statistics and Probability

Chapter 2: Probability

Practice

Instructions: Click the Download File button to download a printable PDF of the questions. Answer each of the following practice questions on a separate piece of paper. Step by step solutions are provided under the Solutions tab. You will learn the material more thoroughly if you complete the questions before checking the answers.

Download File

Practice
Solutions

The odds in favour of rolling a 10 on a multi-sided die are 1:11. Calculate the probability of rolling a 10.
The odds against winning a raffle are 243:2. Determine the probability of winning the raffle.

Question 1

The odds in favour of rolling a 10 on a multi-sided die are 1:11. Calculate the probability of rolling a 10.

Solution

\begin{array}{rcl} odds in favour & = & number of favourable outcomes : number of unfavourable outcomes \\ = & 1 : 11 \end{array}

Complete the table.

favourable outcomes (rolling a 10)	1
unfavourable outcomes (not rolling a 10)	11
total outcomes	12

Find the probability.

\begin{array}{rcl} probability & = & \frac{number of sides with a 10}{total number of sides} \\ = & \frac{1}{12} \end{array}

The probability of rolling a 10 is

\frac{1}{12}

Question 2

The odds against winning a raffle are 243:2. Determine the probability of winning the raffle.

Solution

\begin{array}{rcl} odds against & = & number of unfavourable outcomes : number of favourable outcomes \\ = & 243 : 2 \end{array}

favourable outcomes (winning tickets)	2
unfavourable outcomes (non-winning tickets)	243
total outcomes	245

Calculate the probability.

\begin{array}{rcl} probability & = & \frac{number of favourable outcomes}{total number of possible outcomes} \\ = & \frac{2}{245} \end{array}

The probability of winning the raffle is

\frac{2}{245}