The average height of some boys is 136 cm. When 3 girls, with a total height of 324 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 |
136 |
|
130 |
Total value |
136 u |
324 |
130 u + 390 |
Total height of the boys
= 1 u x 136
= 136 u
Total height of the children = 136 u + 324
136 u + 324 = 130 u + 390
136 u - 130 u = 390 - 324
6 u = 66
1 u = 66 ÷ 6 = 11
Total number of children
= 1 u + 3
= 11 + 3
= 14
Answer(s): 14