The average height of some boys is 149 cm. When 3 girls, with a total height of 375 cm, are included, the average height if the children becomes 140 cm. How many children are there altogether?
|
Boys |
Girls |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
149 |
|
140 |
Total value |
149 u |
375 |
140 u + 420 |
Total height of the boys
= 1 u x 149
= 149 u
Total height of the children = 149 u + 375
149 u + 375 = 140 u + 420
149 u - 140 u = 420 - 375
9 u = 45
1 u = 45 ÷ 9 = 5
Total number of children
= 1 u + 3
= 5 + 3
= 8
Answer(s): 8