The average height of some girls is 143 cm. When 3 boys, with a total height of 363 cm, are included, the average height if the children becomes 137 cm. How many children are there altogether?
|
Girls |
Boys |
Total |
Number |
1 u |
3 |
1 u + 3 |
Value |
143 |
|
137 |
Total value |
143 u |
363 |
137 u + 411 |
Total height of the girls
= 1 u x 143
= 143 u
Total height of the children = 143 u + 363
143 u + 363 = 137 u + 411
143 u - 137 u = 411 - 363
6 u = 48
1 u = 48 ÷ 6 = 8
Total number of children
= 1 u + 3
= 8 + 3
= 11
Answer(s): 11