The average height of some boys is 143 cm. When 3 girls, with a total height of 366 cm, are included, the average height if the children becomes 134 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
143 |
|
134 |
Total value |
143 u |
366 |
134 u + 402 |
Total height of the boys
= 1 u x 143
= 143 u
Total height of the children = 143 u + 366
143 u + 366 = 134 u + 402
143 u - 134 u = 402 - 366
9 u = 36
1 u = 36 ÷ 9 = 4
Total number of children
= 1 u + 3
= 4 + 3
= 7
Answer(s): 7