The average height of some girls is 126 cm. When 3 boys, with a total height of 318 cm, are included, the average height if the children becomes 121 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
126 |
|
121 |
Total value |
126 u |
318 |
121 u + 363 |
Total height of the girls
= 1 u x 126
= 126 u
Total height of the children = 126 u + 318
126 u + 318 = 121 u + 363
126 u - 121 u = 363 - 318
5 u = 45
1 u = 45 ÷ 5 = 9
Total number of children
= 1 u + 3
= 9 + 3
= 12
Answer(s): 12