The average height of some boys is 134 cm. When 3 girls, with a total height of 378 cm, are included, the average height if the children becomes 130 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
134 |
|
130 |
Total value |
134 u |
378 |
130 u + 390 |
Total height of the boys
= 1 u x 134
= 134 u
Total height of the children = 134 u + 378
134 u + 378 = 130 u + 390
134 u - 130 u = 390 - 378
4 u = 12
1 u = 12 ÷ 4 = 3
Total number of children
= 1 u + 3
= 3 + 3
= 6
Answer(s): 6