The average height of some girls is 137 cm. When 3 boys, with a total height of 375 cm, are included, the average height if the children becomes 131 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
137 |
|
131 |
Total value |
137 u |
375 |
131 u + 393 |
Total height of the girls
= 1 u x 137
= 137 u
Total height of the children = 137 u + 375
137 u + 375 = 131 u + 393
137 u - 131 u = 393 - 375
6 u = 18
1 u = 18 ÷ 6 = 3
Total number of children
= 1 u + 3
= 3 + 3
= 6
Answer(s): 6