The average height of some boys is 150 cm. When 3 girls, with a total height of 354 cm, are included, the average height if the children becomes 142 cm. How many children are there altogether?
| |
Boys |
Girls |
Total |
| Number |
1 u |
3 |
1 u + 3 |
| Value |
150 |
|
142 |
| Total value |
150 u |
354 |
142 u + 426 |
Total height of the boys
= 1 u x 150
= 150 u
Total height of the children = 150 u + 354
150 u + 354 = 142 u + 426
150 u - 142 u = 426 - 354
8 u = 72
1 u = 72 ÷ 8 = 9
Total number of children
= 1 u + 3
= 9 + 3
= 12
Answer(s): 12
