315 people went to a zoo.
35 were adults. Some children joined halfway and the ratio of the number of adults to the number of children became 9 : 10. How many children joined the zoo halfway?
| |
Adults |
Children |
Total |
| Before |
3x3 =
9 u |
2x3 =
6 u |
5x3 =
15 u |
| Change |
|
+ ? |
|
| After |
9 u |
10 u |
|
Fraction of the people that were children at first
= 1 -
35 =
25 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 = 15 u
15 u = 315
1 u = 315 ÷ 15 = 21
Number of children who joined halfway
= 10 u - 6 u
= 4 u
= 4 x 21
= 84
Answer(s): 84
