280 people went to a park.
57 were adults. Some children joined halfway and the ratio of the number of adults to the number of children became 10 : 7. How many children joined the park halfway?
| |
Adults |
Children |
Total |
| Before |
5x2 =
10 u |
2x2 =
4 u |
7x2 =
14 u |
| Change |
|
+ ? |
|
| After |
10 u |
7 u |
|
Fraction of the people that were children at first
= 1 -
57 =
27 Number of adults remains unchanged. Make the number of adults the same. LCM of 5 and 10 is 10.
Total number of people at first = 14 u
14 u = 280
1 u = 280 ÷ 14 = 20
Number of children who joined halfway
= 7 u - 4 u
= 3 u
= 3 x 20
= 60
Answer(s): 60
