The average height of some boys is 135 cm. When 3 girls, with a total height of 360 cm, are included, the average height if the children becomes 132 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
135 |
|
132 |
Total value |
135 u |
360 |
132 u + 396 |
Total height of the boys
= 1 u x 135
= 135 u
Total height of the children = 135 u + 360
135 u + 360 = 132 u + 396
135 u - 132 u = 396 - 360
3 u = 36
1 u = 36 ÷ 3 = 12
Total number of children
= 1 u + 3
= 12 + 3
= 15
Answer(s): 15