The average height of some girls is 148 cm. When 3 boys, with a total height of 363 cm, are included, the average height if the children becomes 139 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
148 |
|
139 |
Total value |
148 u |
363 |
139 u + 417 |
Total height of the girls
= 1 u x 148
= 148 u
Total height of the children = 148 u + 363
148 u + 363 = 139 u + 417
148 u - 139 u = 417 - 363
9 u = 54
1 u = 54 ÷ 9 = 6
Total number of children
= 1 u + 3
= 6 + 3
= 9
Answer(s): 9