The average height of some girls is 134 cm. When 3 boys, with a total height of 372 cm, are included, the average height if the children becomes 131 cm. How many children are there altogether?
| |
Girls |
Boys |
Total |
| Number |
1 u |
3 |
1 u + 3 |
| Value |
134 |
|
131 |
| Total value |
134 u |
372 |
131 u + 393 |
Total height of the girls
= 1 u x 134
= 134 u
Total height of the children = 134 u + 372
134 u + 372 = 131 u + 393
134 u - 131 u = 393 - 372
3 u = 21
1 u = 21 ÷ 3 = 7
Total number of children
= 1 u + 3
= 7 + 3
= 10
Answer(s): 10
