The average height of some boys is 130 cm. When 3 girls, with a total height of 348 cm, are included, the average height if the children becomes 124 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
130 |
|
124 |
Total value |
130 u |
348 |
124 u + 372 |
Total height of the boys
= 1 u x 130
= 130 u
Total height of the children = 130 u + 348
130 u + 348 = 124 u + 372
130 u - 124 u = 372 - 348
6 u = 24
1 u = 24 ÷ 6 = 4
Total number of children
= 1 u + 3
= 4 + 3
= 7
Answer(s): 7