The average height of some girls is 130 cm. When 3 boys, with a total height of 300 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 |
130 |
|
124 |
Total value |
130 u |
300 |
124 u + 372 |
Total height of the girls
= 1 u x 130
= 130 u
Total height of the children = 130 u + 300
130 u + 300 = 124 u + 372
130 u - 124 u = 372 - 300
6 u = 72
1 u = 72 ÷ 6 = 12
Total number of children
= 1 u + 3
= 12 + 3
= 15
Answer(s): 15