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Lesson 28 — Activity 2: Mean and Median
Lesson 28 — Activity 2:
Mean
and
Median
Getting Ready
Two other ways to look at statistics are to calculate the mean and median of a set of numbers.
You will practise calculating these in this activity.
Let's look at calculating the mean first.
To calculate the mean of a set of numbers, simply add up all of the numbers and divide by the amount of numbers you have.
Look at these numbers:
17, 42, 53, 16, and 23
What is the mean? Just as in the last activity, you should put the numbers in order from lowest to highest first before calculating the mean.
17, 42, 53, 16, 23 ordered becomes:
16, 17, 23, 42, 53

Add up the numbers.
16 + 17 + 23 + 42 + 53 = 151

Divide the total by the amount of numbers you have. In this case, you have five numbers.
151 ÷ 5 = 30.2
The mean for this set of numbers is 30.2.
Try This:
Look at this set of numbers. Find the mean. You may use a calculator to solve.
94, 84, 69, 75, 90, 9, 5
The numbers ordered are: 5, 9, 69, 75, 84, 90, 94
5 + 9 + 69 + 75 + 84 + 90 + 94 = 426
426 ÷ 7 = 60.9
The mean is 60.9.
The median of a set of numbers is the middle number of the set.
If you look at the numbers from the example above:
16, 17, 23, 42, 53
the middle number is 23. Therefore the median is 23. If you have an odd group of numbers in your data, the median is simply the middle number. However, if you have an even group of numbers in your data, you have to do a little math to find the median.
Let's add one more number to our list above. Let's add the number 100 to the list.
17, 42, 53, 16, 23, 100 ordered becomes: 16, 17, 23, 42, 53, 100
Notice that there are now six numbers in the list. There isn't a middle number. When this occurs, you have to find the two middle numbers and average them. In this case, the middle numbers are 23 and 42. In order to find the median, add the two numbers together and divide the total by 2.
23 + 42 = 65
65 ÷ 2 = 32.5
The median is 32.5.
Now Try This:
Look once again at this set of numbers (with a new number added):
94, 84, 69, 75, 90, 9, 5, 21
Find the median. Don't forget to order the numbers first. You may use a calculator to solve.
The numbers ordered are: 5, 9, 21, 69, 75, 84, 90, 94
The two middle numbers are 69 and 75.
69 + 75 = 144
144 ÷ 2 = 72
The median is 72.