The average height of some boys is 147 cm. When 3 girls, with a total height of 366 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 |
147 |
|
142 |
Total value |
147 u |
366 |
142 u + 426 |
Total height of the boys
= 1 u x 147
= 147 u
Total height of the children = 147 u + 366
147 u + 366 = 142 u + 426
147 u - 142 u = 426 - 366
5 u = 60
1 u = 60 ÷ 5 = 12
Total number of children
= 1 u + 3
= 12 + 3
= 15
Answer(s): 15