The average height of some girls is 149 cm. When 3 boys, with a total height of 417 cm, are included, the average height if the children becomes 144 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
149 |
|
144 |
Total value |
149 u |
417 |
144 u + 432 |
Total height of the girls
= 1 u x 149
= 149 u
Total height of the children = 149 u + 417
149 u + 417 = 144 u + 432
149 u - 144 u = 432 - 417
5 u = 15
1 u = 15 ÷ 5 = 3
Total number of children
= 1 u + 3
= 3 + 3
= 6
Answer(s): 6