The average height of some girls is 124 cm. When 3 boys, with a total height of 336 cm, are included, the average height if the children becomes 121 cm. How many children are there altogether?
| |
Girls |
Boys |
Total |
| Number |
1 u |
3 |
1 u + 3 |
| Value |
124 |
|
121 |
| Total value |
124 u |
336 |
121 u + 363 |
Total height of the girls
= 1 u x 124
= 124 u
Total height of the children = 124 u + 336
124 u + 336 = 121 u + 363
124 u - 121 u = 363 - 336
3 u = 27
1 u = 27 ÷ 3 = 9
Total number of children
= 1 u + 3
= 9 + 3
= 12
Answer(s): 12
