The average height of some boys is 147 cm. When 3 girls, with a total height of 363 cm, are included, the average height if the children becomes 141 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
147 |
|
141 |
Total value |
147 u |
363 |
141 u + 423 |
Total height of the boys
= 1 u x 147
= 147 u
Total height of the children = 147 u + 363
147 u + 363 = 141 u + 423
147 u - 141 u = 423 - 363
6 u = 60
1 u = 60 ÷ 6 = 10
Total number of children
= 1 u + 3
= 10 + 3
= 13
Answer(s): 13