The average height of some boys is 124 cm. When 3 girls, with a total height of 345 cm, are included, the average height if the children becomes 121 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
124 |
|
121 |
Total value |
124 u |
345 |
121 u + 363 |
Total height of the boys
= 1 u x 124
= 124 u
Total height of the children = 124 u + 345
124 u + 345 = 121 u + 363
124 u - 121 u = 363 - 345
3 u = 18
1 u = 18 ÷ 3 = 6
Total number of children
= 1 u + 3
= 6 + 3
= 9
Answer(s): 9