The average height of some boys is 146 cm. When 3 girls, with a total height of 372 cm, are included, the average height if the children becomes 140 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
146 |
|
140 |
Total value |
146 u |
372 |
140 u + 420 |
Total height of the boys
= 1 u x 146
= 146 u
Total height of the children = 146 u + 372
146 u + 372 = 140 u + 420
146 u - 140 u = 420 - 372
6 u = 48
1 u = 48 ÷ 6 = 8
Total number of children
= 1 u + 3
= 8 + 3
= 11
Answer(s): 11