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Growing Families

Age 14 to 16 Short Challenge Level:

a) To find the average number of children per family, we need to know the total number of children, and divide this by the total number of families.

Some more rows and columns have been added to the table below.

Number of children 1 2 3 4 5 total
Number of families 6 13 9 4 1 33
Total number of
children in families
this size
1$\times$6 
= 6
2$\times$13
= 26
3$\times$9 
= 27
4$\times$4 
= 16
5$\times$1 
= 5
80

80$\div$33 = 2.42


b) To find the average number of siblings, we need to add even more columns to the table. We need to know the total number of siblings of all of the children combined, and divide this by the total number of children.
 

Number of children 1 2 3 4 5 total
Number of families 6 13 9 4 1  
Total number of
children in families
this size
1$\times$6 
= 6
2$\times$13
= 26
3$\times$9 
= 27
4$\times$4 
= 16
5$\times$1 
= 5
80
Number of siblings
each child in this
size family has
0 1 2 3 4  
Total number of
siblings in families
this size
0$\times$6 
= 0
1$\times$26
= 26
2$\times$27
= 54
3$\times$16
= 48
4$\times$5 
= 20
148

148$\div$80 = 1.85

You can find more short problems, arranged by curriculum topic, in our short problems collection.