The average height of some girls is 122 cm. When 3 boys, with a total height of 312 cm, are included, the average height if the children becomes 113 cm. How many children are there altogether?
| |
Girls |
Boys |
Total |
| Number |
1 u |
3 |
1 u + 3 |
| Value |
122 |
|
113 |
| Total value |
122 u |
312 |
113 u + 339 |
Total height of the girls
= 1 u x 122
= 122 u
Total height of the children = 122 u + 312
122 u + 312 = 113 u + 339
122 u - 113 u = 339 - 312
9 u = 27
1 u = 27 ÷ 9 = 3
Total number of children
= 1 u + 3
= 3 + 3
= 6
Answer(s): 6
