Evelyn's school organized a trip to Brunei. At first, the ratio of the number of girls to the number of boys who planned to participate in the trip was 8 : 7. On the day of registration, 20 boys decided to withdraw and 20 more girls decided to join in. In the end, the number of boys who participated became 30% of the total children for the trip. How many children would visit Brunei in the end?
|
Girls |
Boys |
Total |
Before |
8x2 = 16 u |
7x2 = 14 u |
15x2 = 30 u |
Change |
+ 5 u |
- 5 u |
|
After |
7x3 = 21 u |
3x3 = 9 u |
10x3 = 30 u |
30% =
30100 =
310Since 20 boys withdrew and another 20 girls joined, the total number of children at first and in the end remains unchanged. Make the total number of children the same. LCM of 15 and 10 is 30.
Number of boys who decided to withdraw
= 14 u - 9 u
= 5 u
5 u = 20
1 u = 20 ÷ 5 = 4
Number of children that would visit Brunei in the end
= 21 u + 9 u
= 30 u
= 30 x 4
= 120
Answer(s): 120