The average height of some boys is 146 cm. When 3 girls, with a total height of 348 cm, are included, the average height if the children becomes 137 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
146 |
|
137 |
Total value |
146 u |
348 |
137 u + 411 |
Total height of the boys
= 1 u x 146
= 146 u
Total height of the children = 146 u + 348
146 u + 348 = 137 u + 411
146 u - 137 u = 411 - 348
9 u = 63
1 u = 63 ÷ 9 = 7
Total number of children
= 1 u + 3
= 7 + 3
= 10
Answer(s): 10