The frequency is the number of times an event occurs; or the number of individuals (people, animals etc.) with some specific property.

An interval is all the values between two points. e.g. 4 < x ≤ 10

Calculating the mean from a grouped frequency table

Maths

In this unit, pupils began to compare two different sets of data. In the future unit, pupils will consider cumulative frequency graphs and histograms and compare the data from these diagrams to other graphical representations.

In the prior unit, pupils considered the mean, median and mode and evaluated their usefulness in a variety of contexts. In this unit, pupils extend this learning to comparing two different data sets and comparing these measures of central tendency.

Comparisons of numerical summaries of data

An estimate for the total number of litres used by the 10 people who each used between 40 and 60 litres is {{ }} litres.

Estimates of $$a$$ and $$b$$ cannot be found

A supermarket manager records the total number of shoppers each day for a month. The table shows her results.
The estimate for the total number of shoppers in this data set is {{ }} shoppers. 

Both $$a$$ and $$b$$ are the totals of their columns. Which of these statements are correct?

The table shows some pupils' marks in an exam. The estimated mean score to the nearest integer is {{ }} marks. 

The sum of the 10 data points in a data set is 180. The mean of this data set is {{ }}.

Match each summary statistic to its value for a data set of: 1, 3, 6, 10, 13, 15, 15.

In total, many people are there in this data set? 

The table shows the number of pets owned by some volunteers at an animal rescue centre. Calculate the mean number of pets. 

15 people had grass 20 cm long, and 15 people had grass 40 cm long.

15 people had grass between 20 cm and 40 cm long.

This grouped frequency table shows the length of grass in different people’s gardens. What does the highlighted row of this grouped frequency table mean?

The average expected range of this data set is {{ }}.

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