The average height of some girls is 133 cm. When 3 boys, with a total height of 309 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 |
133 |
|
124 |
Total value |
133 u |
309 |
124 u + 372 |
Total height of the girls
= 1 u x 133
= 133 u
Total height of the children = 133 u + 309
133 u + 309 = 124 u + 372
133 u - 124 u = 372 - 309
9 u = 63
1 u = 63 ÷ 9 = 7
Total number of children
= 1 u + 3
= 7 + 3
= 10
Answer(s): 10