The average height of some boys is 122 cm. When 3 girls, with a total height of 312 cm, are included, the average height if the children becomes 116 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
122 |
|
116 |
Total value |
122 u |
312 |
116 u + 348 |
Total height of the boys
= 1 u x 122
= 122 u
Total height of the children = 122 u + 312
122 u + 312 = 116 u + 348
122 u - 116 u = 348 - 312
6 u = 36
1 u = 36 ÷ 6 = 6
Total number of children
= 1 u + 3
= 6 + 3
= 9
Answer(s): 9