240 people went to a museum.
58 were adults. Some children left halfway and the ratio of the number of adults to the number of children became 15 : 7. How many children left the museum halfway?
| |
Adults |
Children |
Total |
| Before |
5x3 =
15 u |
3x3 =
9 u |
8x3 =
24 u |
| Change |
|
- ? |
|
| After |
15 u |
7 u |
|
Fraction of the people that were children at first
= 1 -
58 =
38 Number of adults remains unchanged. Make the number of adults the same. LCM of 5 and 15 is 15.
Total number of people at first = 24 u
24 u = 240
1 u = 240 ÷ 24 = 10
Number of children who left halfway
= 9 u - 7 u
= 2 u
= 2 x 10
= 20
Answer(s): 20
