Sara wanted to know the ages of the children on the school bus. She conducted a survey and her results are shown below:
To find the mean add all the ages together and divide by the total number of children.
If you type all those ages into a calculator it is easy to make an error.
It can be helpful to see these results displayed in a frequency table:
The frequency table shows us that there are six children aged \({11}\), seven children aged \({12}\), five children aged \({13}\)... etc.
To find the sum of their ages, calculate:
\((6 \times 11) + (7 \times 12) + (5 \times 13)\)\(+ (7 \times 14) + (3 \times 15) + (2 \times 16) = 390\)
The total number of children is \(6 + 7 + 5 + 7 + 3 + 2 = 30\)
So, the mean age is \(390 \div 30 = 13\)
You could also put this information into a table like the one below:
Mean = \(390 \div 30 = 13\)
Find the mean of the shoe sizes of pupils in Mrs Harris’ class:
Mean \(= 108 \div 20 = 5.4\)
Notice that the mean value does not have to be a whole number or an actual shoe size.