### GCSE Maths

Numbers
Algebra
Geometry and Measures
Probability
Statistics

# Probability of Single Events

This topic builds on your previous understanding of probability to include more complicated examples and guides you through the working-out process.

## Example 1: Buttons

Emma has 6 pink, 16 green and 8 blue buttons in a box. What is the probability that she will randomly select a blue button? Write your answer as a percentage.

Solution:

First, calculate the total number of buttons:

• buttons in total.

Next, represent the number of blue buttons as a fraction of the total:

• Finally, since the question asks for the answer in percentage form, convert the fraction to a percentage:

• • ## Example 2: Buttons (continued)

Emma removes 5 pink buttons from the box. What is the probability that she will now select a blue button? Write your answer as a decimal.

Solution:

Calculate the new total number of buttons:

• We must use this number as the new total.

Use this new total to find the fraction representing blue buttons:

• Finally, convert this fraction to a decimal:

• ## Example 3: Numbers on a spinner

Jerry has a fair hexagonal spinner with 6 numbers in total. The probabilities for landing on specific numbers are:

• The probability of landing on a 1 is .
• The probability of landing on a 2 is .
• The probability of landing on a 3 is .

Write the numbers on the spinner.

First, convert each fraction to have a denominator of 6, as there are 6 numbers on this spinner:

• • • Use the numerators to find how many times each number appears on the spinner:

• out of the 6 numbers
• out of the 6 numbers
• out of the 6 numbers

Complete the spinner.

Therefore, on the spinner, the numbers should be distributed based on these probabilities to make it a “fair” spinner. The sum of these probabilities is , confirming it as a fair spinner. Note that the placement of the numbers doesn’t matter.