PSLE Cathy had a bag of brown marbles and pink marbles in the ratio 13 : 7. She removed an equal number of brown marbles and pink marbles from the bag. The ratio of the number of brown marbles and pink marbles left in the bag became 6 : 1. What percentage of the marbles were left in the bag?
|
Brown marbles |
Pink marbles |
Difference |
Total |
Before |
13x5 = 65 u |
7x5 = 35 u |
6x5 = 30 u |
20x5 = 100 u |
Change |
- 29 u |
- 29 u |
|
|
After |
6x6 = 36 u |
1x6 = 6 u |
5x6 = 30 u |
7x6 = 42 u |
When Cathy removed an equal number of brown marbles and pink marbles, the difference between the number of brown marbles and pink marbles at first and in the end remains the same.
LCM of 6 and 5 is 30.
Percentage of the marbles left in the bag
=
42100 x 100%
= 2150 x 100%
= 42%
Answer: 42%