GRAPHS AND STATISTICS

Averages

Learn the reliable method for averages, then apply it to 11+ exam-style questions.

1 · WHAT YOU NEED TO KNOW

The idea

The mean is the total of the values divided by how many values there are.

Picture itShare the total equally
2 · THE METHOD

Follow these steps

  1. Add every value, including repeats.
  2. Count the values.
  3. Divide the total by the count.
mean = total ÷ number of values
3 · WORKED EXAMPLES

See the method in action

Example 1

Find the mean of these values: 8, 11, 11.

  1. Add the values to get 30.
  2. Divide by 3: 30 ÷ 3 = 10.
Answer: 10
Example 2

The mean of five readings is 56. The highest reading, 60, is removed. What is the mean of the remaining readings?

  1. The original total is 56 × 5 = 280.
  2. Remove 60 to leave 220, then divide by 4: 220 ÷ 4 = 55.
Answer: 55
4 · ELEVENSPRINT TIP

A useful shortcut

Divide the total by the count.

5 · COMMON MISTAKES

Watch out for these

6 · TRY IT YOURSELF

Three fresh questions

Ready to check the method? You will get three fresh, validated questions.