The average height of some girls is 148 cm. When 3 boys, with a total height of 339 cm, are included, the average height if the children becomes 141 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
148 |
|
141 |
Total value |
148 u |
339 |
141 u + 423 |
Total height of the girls
= 1 u x 148
= 148 u
Total height of the children = 148 u + 339
148 u + 339 = 141 u + 423
148 u - 141 u = 423 - 339
7 u = 84
1 u = 84 ÷ 7 = 12
Total number of children
= 1 u + 3
= 12 + 3
= 15
Answer(s): 15