120 people went to a zoo.
34 were adults. Some children joined halfway and the ratio of the number of adults to the number of children became 9 : 7. How many children joined the zoo halfway?
| |
Adults |
Children |
Total |
| Before |
3x3 =
9 u |
1x3 =
3 u |
4x3 =
12 u |
| Change |
|
+ ? |
|
| After |
9 u |
7 u |
|
Fraction of the people that were children at first
= 1 -
34 =
14 Number of adults remains unchanged. Make the number of adults the same. LCM of 3 and 9 is 9.
Total number of people at first = 12 u
12 u = 120
1 u = 120 ÷ 12 = 10
Number of children who joined halfway
= 7 u - 3 u
= 4 u
= 4 x 10
= 40
Answer(s): 40
