231 people went to a concert hall.
47 were adults. Some children joined halfway and the ratio of the number of adults to the number of children became 12 : 11. How many children joined the concert hall halfway?
| |
Adults |
Children |
Total |
| Before |
4x3 =
12 u |
3x3 =
9 u |
7x3 =
21 u |
| Change |
|
+ ? |
|
| After |
12 u |
11 u |
|
Fraction of the people that were children at first
= 1 -
47 =
37 Number of adults remains unchanged. Make the number of adults the same. LCM of 4 and 12 is 12.
Total number of people at first = 21 u
21 u = 231
1 u = 231 ÷ 21 = 11
Number of children who joined halfway
= 11 u - 9 u
= 2 u
= 2 x 11
= 22
Answer(s): 22
