720 people went to a zoo.
58 were children. Some adults joined halfway and the ratio of the number of children to the number of adults became 15 : 13. How many adults joined the zoo halfway?
| |
Children |
Adults |
Total |
| Before |
5x3 =
15 u |
3x3 =
9 u |
8x3 =
24 u |
| Change |
|
+ ? |
|
| After |
15 u |
13 u |
|
Fraction of the people that were adults at first
= 1 -
58 =
38 Number of children remains unchanged. Make the number of children the same. LCM of 5 and 15 is 15.
Total number of people at first = 24 u
24 u = 720
1 u = 720 ÷ 24 = 30
Number of adults who joined halfway
= 13 u - 9 u
= 4 u
= 4 x 30
= 120
Answer(s): 120
