The average height of some boys is 127 cm. When 3 girls, with a total height of 321 cm, are included, the average height if the children becomes 123 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
127 |
|
123 |
Total value |
127 u |
321 |
123 u + 369 |
Total height of the boys
= 1 u x 127
= 127 u
Total height of the children = 127 u + 321
127 u + 321 = 123 u + 369
127 u - 123 u = 369 - 321
4 u = 48
1 u = 48 ÷ 4 = 12
Total number of children
= 1 u + 3
= 12 + 3
= 15
Answer(s): 15