The average height of some girls is 131 cm. When 3 boys, with a total height of 369 cm, are included, the average height if the children becomes 128 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
131 |
|
128 |
Total value |
131 u |
369 |
128 u + 384 |
Total height of the girls
= 1 u x 131
= 131 u
Total height of the children = 131 u + 369
131 u + 369 = 128 u + 384
131 u - 128 u = 384 - 369
3 u = 15
1 u = 15 ÷ 3 = 5
Total number of children
= 1 u + 3
= 5 + 3
= 8
Answer(s): 8