168 people went to a concert hall.
27 were adults. Some children left halfway and the ratio of the number of adults to the number of children became 4 : 7. How many children left the concert hall halfway?
|
Adults |
Children |
Total |
Before |
2x2 = 4 u |
5x2 = 10 u |
7x2 = 14 u |
Change |
|
- ? |
|
After |
4 u |
7 u |
|
Fraction of the people that were children at first
= 1 -
27 =
57 Number of adults remains unchanged. Make the number of adults the same. LCM of 2 and 4 is 4.
Total number of people at first = 14 u
14 u = 168
1 u = 168 ÷ 14 = 12
Number of children who left halfway
= 10 u - 7 u
= 3 u
= 3 x 12
= 36
Answer(s): 36