150 people went to a zoo.
35 were children. Some adults left halfway and the ratio of the number of children to the number of adults became 9 : 4. How many adults left the zoo halfway?
| |
Children |
Adults |
Total |
| Before |
3x3 =
9 u |
2x3 =
6 u |
5x3 =
15 u |
| Change |
|
- ? |
|
| After |
9 u |
4 u |
|
Fraction of the people that were adults at first
= 1 -
35 =
25 Number of children remains unchanged. Make the number of children the same. LCM of 3 and 9 is 9.
Total number of people at first = 15 u
15 u = 150
1 u = 150 ÷ 15 = 10
Number of adults who left halfway
= 6 u - 4 u
= 2 u
= 2 x 10
= 20
Answer(s): 20
