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Maths

Tallying, collecting and grouping data

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# Collecting data

The easiest way to collect data is to use a tally chart.

When collecting data for the number of pets survey, it would have been useful to draw a table similar to this one.

As each person answers the question, we put a tally next to the appropriate number of pets. The frequency column is completed once all of the data has been collected. The table below shows the results of a new pets survey.

## Number of pets survey

Number of petsTallyFrequency
03
18
212
31
42

These frequencies can be displayed in a bar chart, as shown.

Frequency means the 'number of times it occurs'.

In this example, three people had no pets, so the frequency of 0 pets was three.

Remember that the total frequency should be the same as the number of people in your survey. Always check that this is correct.

In this example, we know that 26 people were questioned in the survey. Check this by adding up the frequency totals: 3 + 8 + 12 + 1 + 2 = 26

Here is the same information but this time we have two tables, one for the number of pets owned by boys and one for the number of pets owned by girls.

## Number of pets owned by boys

Number of petsTallyFrequency
02
13
25
31
41

## Number of pets owned by girls

Number of petsTallyFrequency
01
15
27
30
41

These frequencies can be displayed in a dual bar chart.

We can find more information from looking at this graph.

Question

How many pets were owned by the same number of boys as for girls?

Answer

Four pets.

We can see that the height of the bar is the same for both boys and girls for four pets.

Question

How many more girls than boys were there in the survey?

Answer

Two more girls.

Adding the bars for girls and for boys we find:

• the total for girls is: 1 + 5 + 7 + 0 + 1 = 14
• the total boys is: 2 + 3 + 5 + 1 + 1= 12

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