The average height of some girls is 147 cm. When 3 boys, with a total height of 414 cm, are included, the average height if the children becomes 144 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
147 |
|
144 |
Total value |
147 u |
414 |
144 u + 432 |
Total height of the girls
= 1 u x 147
= 147 u
Total height of the children = 147 u + 414
147 u + 414 = 144 u + 432
147 u - 144 u = 432 - 414
3 u = 18
1 u = 18 ÷ 3 = 6
Total number of children
= 1 u + 3
= 6 + 3
= 9
Answer(s): 9