The average mass of a group of girls was 37 kg. When a boy, Warren, joined the group, the average mass of the group became 32 kg. If Warren had a mass of 22 kg, how many girls were there in the group in the end?
|
At first |
In the end |
Number |
1 u |
1 u + 1 |
Value |
37 |
32 |
Total value |
37 u |
32 u + 32 |
37 u + 22 = 32 u + 32
37 u - 32 u = 32 - 22
5 u = 10
1 u = 10 ÷ 5 = 2
Number of girls in the group in the end = 2
Answer(s): 2