Lily's school organized a trip to Haiti. At first, the ratio of the number of girls to the number of boys who planned to participate in the trip was 7 : 5. On the day of registration, 117 boys decided to withdraw and 117 more girls decided to join in. In the end, the number of boys who participated became 20% of the total children for the trip. How many less boys than girls would visit Haiti in the end?
|
Girls |
Boys |
Total |
Before |
7x5 = 35 u |
5x5 = 25 u |
12x5 = 60 u |
Change |
+ 13 u |
- 13 u |
|
After |
4x12 = 48 u |
1x12 = 12 u |
5x12 = 60 u |
20% =
20100 =
15Since 117 boys withdrew and another 117 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 12 and 5 is 60.
Number of boys who decided to withdraw
= 25 u - 12 u
= 13 u
13 u = 117
1 u = 117 ÷ 13 = 9
Number of less boys than girls in the end
= 48 u - 12 u
= 36 u
= 36 x 9
= 324
Answer(s): 324