230 people went to a zoo.
25 were adults. Some children joined halfway and the ratio of the number of adults to the number of children became 4 : 9. How many children joined the zoo halfway?
| |
Adults |
Children |
Total |
| Before |
2x2 =
4 u |
3x2 =
6 u |
5x2 =
10 u |
| Change |
|
+ ? |
|
| After |
4 u |
9 u |
|
Fraction of the people that were children at first
= 1 -
25 =
35 Number of adults remains unchanged. Make the number of adults the same. LCM of 2 and 4 is 4.
Total number of people at first = 10 u
10 u = 230
1 u = 230 ÷ 10 = 23
Number of children who joined halfway
= 9 u - 6 u
= 3 u
= 3 x 23
= 69
Answer(s): 69
