The average height of some girls is 141 cm. When 3 boys, with a total height of 333 cm, are included, the average height if the children becomes 132 cm. How many children are there altogether?
| |
Girls |
Boys |
Total |
| Number |
1 u |
3 |
1 u + 3 |
| Value |
141 |
|
132 |
| Total value |
141 u |
333 |
132 u + 396 |
Total height of the girls
= 1 u x 141
= 141 u
Total height of the children = 141 u + 333
141 u + 333 = 132 u + 396
141 u - 132 u = 396 - 333
9 u = 63
1 u = 63 ÷ 9 = 7
Total number of children
= 1 u + 3
= 7 + 3
= 10
Answer(s): 10
