A box of paperclips says 'average contents 100'. But how many are really in there?
Handling Data 2 (Difficult)
Handling data helps you make sense of information. In 11 Plus Maths, you’ll explore averages, probability, and how data can tell us interesting stories about numbers.
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(quiz starts below)
Fascinating Fact:
If you take the mean of 8, 10, and 12, you get 10, the middle ground where all numbers agree to meet for tea.
In 11 Plus Maths, pupils explore how data can be collected, organised, and analysed. They learn how to use averages like the mean, median, and mode to summarise information clearly.
Key Terms
Mean: The average found by adding all numbers together and dividing by how many there are.
Median: The middle number in a list when all numbers are in order.
Mode: The number that appears most often in a data set.
A poll was taken, asking 8 people how many pets they had. Here are the results: 0, 7, 3, 1, 0, 2, 0, 1.
What is the range of the given data?
8
0
7
6
Range = highest value - lowest value = 7 - 0 = 7
2 .
Sarah counted the number of vehicles which passed her school over the course of one hour. She did this every day for a week and got these results: 180, 164, 212, 197, 207, 222, 146.
What is the mean of the given data?
1,328
197
189.7
Impossible to work out
Mean = (the sum of the data values) ÷ the number of data values. The sum of the data values = 180 + 164 + 212 + 197 + 207 + 222 + 146 = 1,328. The number of data values = 7 ? mean = 1,328 ÷ 7 = 189.7 (1 decimal place)
3 .
Michael asked 10 of his friends how many times they had been to watch a live football match. Here are his results: 40, 27, 18, 36, 0, 7, 16, 0, 2, 12.
What is the mode of the given data?
14
15.8
12
0
The mode is the data value that occurs most often: there are two zeros so that is the mode.
4 .
Jane wanted to know how old the men in her family were when they began shaving. She asked 9 of them and got these results: 15, 16, 17, 18, 16, 15, 17, 19, 20.
What is the median of the given data?
18
16
17
19
The median is the middle value of the data: you have to arrange the data in order BEFORE you can find it: 15, 15, 16, 16, 17, 17, 18, 19, 20.. You have nine values, so the median is the 5th value = 17. It is usually best to arrange the data in ascending order.
5 .
Steven asked some of his classmates how many brothers or sisters they had. Here’s his results: 2, 3, 0, 0, 1, 0, 2, 0, 1, 3, 5, 0, 1, 2, 0.
How many of Steven’s classmates took part in the survey?
14
15
16
20
You have 15 data values: each value corresponds to one person. DON'T make the mistake of calling the sum of the data values the number of people: it is NOT 20
6 .
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?
150 cm
148 cm
151 cm
145 cm
Originally there were five pieces of data, with a mean of 144: 144 x 5 = 720.
Adding one extra piece of data means that there are now six of them. 6 x 145 = 870.
To find Clare's height just subtract 720 from 870: 870 - 720 = 150. Clare is 150 cm tall.
7 .
From the following set of data, which average is lowest: the mean, the median or the mode?
18, 21, 22, 19, 20, 21, 21.
The mean
The median
The mode
They are all the same
The mode is 21, as this appears most often. The median is also 21, as the middle value is 21 if arranged from lowest to highest. The mean is worked out by adding all the values and dividing the result by 7: 18 + 21 + 22 + 19 + 20 + 21 + 21 = 142. 142 ÷ 7 = 20.3 (to one decimal place), which is the lowest.
8 .
From the following set of data, which average is highest: the mean, the median or the mode?
75, 48, 82, 65, 70, 68, 75.
The mean
The median
The mode
They are all the same
The mean is worked out by adding all the values and dividing the result by 7: 75 + 48 + 82 + 65 + 70 + 68 + 75 = 483. 483 ÷ 7 = 69.
The median is 70 as this is the middle value if arranged from lowest to highest.
The mode is 75, as this appears most often. This is higher than 70 and 69.
9 .
Which of the following statements is correct?
The median is the value which appears most often
The mode is the middle value if the data is arranged from smallest to largest
The median is the middle value if the data is arranged from smallest to largest
The mode might not appear in the set of data
Median sounds a bit like medium - that's one way to remember that the median is the medium, or middle, value
10 .
Which of the following statements is false?
The mode is always one of the values in a set of data
The mode always appears more than any other value
The median always appears in the set of data
The mean always includes a fraction or a decimal
The mean can SOMETIMES include a fration or a decimal (the mean of 2 and 3 is 2.5 for example), but not always (the mean of 1 and 3 is 2).
Author:
Frank Evans (Specialist 11 Plus Teacher and Tutor)