The average height of some girls is 128 cm. When 3 boys, with a total height of 324 cm, are included, the average height if the children becomes 124 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
128 |
|
124 |
Total value |
128 u |
324 |
124 u + 372 |
Total height of the girls
= 1 u x 128
= 128 u
Total height of the children = 128 u + 324
128 u + 324 = 124 u + 372
128 u - 124 u = 372 - 324
4 u = 48
1 u = 48 ÷ 4 = 12
Total number of children
= 1 u + 3
= 12 + 3
= 15
Answer(s): 15