The average height of some boys is 134 cm. When 3 girls, with a total height of 339 cm, are included, the average height if the children becomes 125 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
134 |
|
125 |
Total value |
134 u |
339 |
125 u + 375 |
Total height of the boys
= 1 u x 134
= 134 u
Total height of the children = 134 u + 339
134 u + 339 = 125 u + 375
134 u - 125 u = 375 - 339
9 u = 36
1 u = 36 ÷ 9 = 4
Total number of children
= 1 u + 3
= 4 + 3
= 7
Answer(s): 7