Charlotte wanted to find out the average height of her friends. She collected these results: 143 cm, 139 cm, 145 cm, 149 cm, 144 cm. The mean of these results was 144 cm. She then measured one more friend, Clare, and the mean rose to 145 cm. How tall was Clare?

Four things are associated with data handling: the range, the mean, the mode and the median. These four ideas are used to work out averages.

The range of a set of data is the difference between its highest and lowest values. The mean is worked out by adding all the values together, then dividing by the number of values. The mode is the value which appears most often. Finally, the median is the middle value of the data, if it is arranged from lowest to highest.

 

Related: 11 Plus (11+) Maths Practice Test: Handling Data (Difficult)