AVERAGES

To find an average, divide the total by the total number of groups or sets.

Average =                    Total                  
                  Total number of groups/sets

 

Examples:

1. What is the average of 12, 20, 35 and 41?

Total = 12 + 20 + 35 + 41
= 108

Average = 108
                   4
= 27
 
 

2. The average weight of 3 girls is 30 kg. Alice weighs 22.5 kg and Belinda weighs 20.8 kg. What is the weight of the third girl?

Total weight of all the 3 girls = 30 x 3
= 90 kg 

Total weight of Alice and Belinda = 22.5 + 20.8
= 43.3 kg

Weight of the third girl = 90 - 43.3
= 46.7 kg

 

3. Mrs Yang's average monthly income is $1 640. Find her total income per year.

Average monthly income = $1 640

Total income per year = $1 640 x 12 
= $19 680 

Mrs Yang's yearly income is $19 680.