The average height of some boys is 131 cm. When 3 girls, with a total height of 357 cm, are included, the average height if the children becomes 128 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
131 |
|
128 |
Total value |
131 u |
357 |
128 u + 384 |
Total height of the boys
= 1 u x 131
= 131 u
Total height of the children = 131 u + 357
131 u + 357 = 128 u + 384
131 u - 128 u = 384 - 357
3 u = 27
1 u = 27 ÷ 3 = 9
Total number of children
= 1 u + 3
= 9 + 3
= 12
Answer(s): 12