The average height of some girls is 126 cm. When 3 boys, with a total height of 318 cm, are included, the average height if the children becomes 122 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
126 |
|
122 |
Total value |
126 u |
318 |
122 u + 366 |
Total height of the girls
= 1 u x 126
= 126 u
Total height of the children = 126 u + 318
126 u + 318 = 122 u + 366
126 u - 122 u = 366 - 318
4 u = 48
1 u = 48 ÷ 4 = 12
Total number of children
= 1 u + 3
= 12 + 3
= 15
Answer(s): 15