The average height of some girls is 127 cm. When 3 boys, with a total height of 321 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 |
127 |
|
122 |
Total value |
127 u |
321 |
122 u + 366 |
Total height of the girls
= 1 u x 127
= 127 u
Total height of the children = 127 u + 321
127 u + 321 = 122 u + 366
127 u - 122 u = 366 - 321
5 u = 45
1 u = 45 ÷ 5 = 9
Total number of children
= 1 u + 3
= 9 + 3
= 12
Answer(s): 12