The average height of some girls is 133 cm. When 3 boys, with a total height of 381 cm, are included, the average height if the children becomes 130 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
133 |
|
130 |
Total value |
133 u |
381 |
130 u + 390 |
Total height of the girls
= 1 u x 133
= 133 u
Total height of the children = 133 u + 381
133 u + 381 = 130 u + 390
133 u - 130 u = 390 - 381
3 u = 9
1 u = 9 ÷ 3 = 3
Total number of children
= 1 u + 3
= 3 + 3
= 6
Answer(s): 6