The average height of some boys is 149 cm. When 3 girls, with a total height of 408 cm, are included, the average height if the children becomes 146 cm. How many children are there altogether?
| |
Boys |
Girls |
Total |
| Number |
1 u |
3 |
1 u + 3 |
| Value |
149 |
|
146 |
| Total value |
149 u |
408 |
146 u + 438 |
Total height of the boys
= 1 u x 149
= 149 u
Total height of the children = 149 u + 408
149 u + 408 = 146 u + 438
149 u - 146 u = 438 - 408
3 u = 30
1 u = 30 ÷ 3 = 10
Total number of children
= 1 u + 3
= 10 + 3
= 13
Answer(s): 13
