A group of skaters are distributed into different weight classes. Here’s a table showing the classes and the frequency of each class.
| Weight || Frequency |
| || 7 |
| || 8 |
| || 12 |
| || 9 |
| || 6 |
Find the mean weight of this group.
- You can see the frequency table of the weight distribution above. The first thing to do is to enter the numbers in
- Add the columns “Midpoint ” and “”. The last column is the product of the midpoint and the frequency. Your table should now look like this:
- As you don’t know the exact weight of everyone in the weight class (it could be anywhere between lb- lb, lb- lb, etc.) you have to assume that the weight of everyone in each weight class is in the exact middle. This would be the average of the numbers 115 and 125 for the first, 125 and 135 for the second, and so on.
Write the following formula in cell
Enter the formula for calculating the mean in the remaining weight classes in the column representing the midpoints.
In the “”-column, write the following formula in cell
D2 and copy the formula all the way down to cell
- Now find the sum of the numbers in the frequency and “” columns. Write the following in cell
And write the following in cell
Finally, you’ll find the mean by dividing the number in cell
D7 by cell
Here are the formulas for each cell:
You can now see that the mean weight for this group is lb.