Image caption, To find the mean age, use a calculator to divide the total age of all the children (168) by how many children there are (15). 168 ÷ 15 = 11.2. The mean age is 11.2 years old.

The main averages, which can also be referred to as measures of central tendency, are the mean, mode and median. Robert is preparing for his Mathematics GCSE exams. Each paper is marked out of 100.

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