The average height of some girls is 131 cm. When 3 boys, with a total height of 333 cm, are included, the average height if the children becomes 126 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
131 |
|
126 |
Total value |
131 u |
333 |
126 u + 378 |
Total height of the girls
= 1 u x 131
= 131 u
Total height of the children = 131 u + 333
131 u + 333 = 126 u + 378
131 u - 126 u = 378 - 333
5 u = 45
1 u = 45 ÷ 5 = 9
Total number of children
= 1 u + 3
= 9 + 3
= 12
Answer(s): 12