The average height of some boys is 129 cm. When 3 girls, with a total height of 357 cm, are included, the average height if the children becomes 124 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
129 |
|
124 |
Total value |
129 u |
357 |
124 u + 372 |
Total height of the boys
= 1 u x 129
= 129 u
Total height of the children = 129 u + 357
129 u + 357 = 124 u + 372
129 u - 124 u = 372 - 357
5 u = 15
1 u = 15 ÷ 5 = 3
Total number of children
= 1 u + 3
= 3 + 3
= 6
Answer(s): 6