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To calculate the mean, we divide the sum of the results by the sample size.

# Unit 4 - Mean

When you have obtained results from your experiment or investigation, you then need to process them. In most investigations, you will have obtained a set of numbers as the results. One way to process these is to calculate the average value. There are three main types of average: median, mode and - the subject of this GCSE Biology quiz - mean.

It is always a good idea to repeat your experiment several times in order to get a larger amount of data. Once who have gathered enough data you can then calculate the mean value. The mean is one particular type of average. To calculate the mean you add up all the values and divide by the number of values in your sample (the sample size). When you work out the mean of a set of results, it is particularly useful as it 'smooths out' the results and gives a more reliable overall answer.

1.
What is the mode for this data? 11, 11, 13, 13, 11, 14, 11, 11, 12
11
12
13
14
It is the most common number in the data set
2.
To calculate the mean, we divide the sum of the results by the...
average
sample size
range
statistic
Larger sample sizes give more reliable results
3.
What is the mean for the values: 13, 18, 13, 14, 13, 16, 14, 21, 13
15
16
17
18
Two thirds of the numbers are less than the average, this shows you how you need to be careful. In an experiment, the values of 18 and 21 could be anomalous results and may need re-checking for accuracy
4.
Find the mean of the following data: 4, 6, 9, 3, 6
5.4
5.5
5.6
5.7
Sum then divide by the sample size
5.
The mode is...
the same thing as mean
equal to the average
the number that is repeated most often
the middle value
In some cases, you would be more interested in the mode than the mean
6.
Mean is also known as the...
mode
median
average
range
Average is a general word that includes the median and the mode so if you are stating that you are going to work out the average value, strictly speaking you would need to specify which one you intended to use
7.
Average can never be the same value as the maximum unless it is ...
the mean
the minimum
the mode
the median
The other types of average must be less than the maximum
8.
The sample size is the...
range
number of results
mode
graph
You only need a sample size of two to calculate the mean
9.
What is the median for this data? 11, 11, 12, 13, 15, 19, 21
11
12
13
21
The median is the middle value. The 4th number in the list of 7 numbers in ascending order
10.
We can use the mean values of a set of results to ...
plot a scatter diagram
write a hypothesis
draw the diagram
write a risk assessment
Adding a line or curve of best fit then shows the correlation between the variables that have been investigated