420 people went to a bird park.
25 were children. Some adults joined halfway and the ratio of the number of children to the number of adults became 6 : 13. How many adults joined the bird park halfway?
| |
Children |
Adults |
Total |
| Before |
2x3 =
6 u |
3x3 =
9 u |
5x3 =
15 u |
| Change |
|
+ ? |
|
| After |
6 u |
13 u |
|
Fraction of the people that were adults at first
= 1 -
25 =
35 Number of children remains unchanged. Make the number of children the same. LCM of 2 and 6 is 6.
Total number of people at first = 15 u
15 u = 420
1 u = 420 ÷ 15 = 28
Number of adults who joined halfway
= 13 u - 9 u
= 4 u
= 4 x 28
= 112
Answer(s): 112
