The average height of some girls is 132 cm. When 3 boys, with a total height of 318 cm, are included, the average height if the children becomes 126 cm. How many children are there altogether?
| |
Girls |
Boys |
Total |
| Number |
1 u |
3 |
1 u + 3 |
| Value |
132 |
|
126 |
| Total value |
132 u |
318 |
126 u + 378 |
Total height of the girls
= 1 u x 132
= 132 u
Total height of the children = 132 u + 318
132 u + 318 = 126 u + 378
132 u - 126 u = 378 - 318
6 u = 60
1 u = 60 ÷ 6 = 10
Total number of children
= 1 u + 3
= 10 + 3
= 13
Answer(s): 13
