The average height of some girls is 141 cm. When 3 boys, with a total height of 351 cm, are included, the average height if the children becomes 133 cm. How many children are there altogether?
| |
Girls |
Boys |
Total |
| Number |
1 u |
3 |
1 u + 3 |
| Value |
141 |
|
133 |
| Total value |
141 u |
351 |
133 u + 399 |
Total height of the girls
= 1 u x 141
= 141 u
Total height of the children = 141 u + 351
141 u + 351 = 133 u + 399
141 u - 133 u = 399 - 351
8 u = 48
1 u = 48 ÷ 8 = 6
Total number of children
= 1 u + 3
= 6 + 3
= 9
Answer(s): 9
