PSLE Fanny had a box of purple marbles and yellow marbles in the ratio 13 : 7. She removed an equal number of purple marbles and yellow marbles from the box. The ratio of the number of purple marbles and yellow marbles left in the box became 4 : 1. What percentage of the marbles were left in the box?
|
Purple marbles |
Yellow marbles |
Difference |
Total |
Before |
13x1 = 13 u |
7x1 = 7 u |
6x1 = 6 u |
20x1 = 20 u |
Change |
- 5 u |
- 5 u |
|
|
After |
4x2 = 8 u |
1x2 = 2 u |
3x2 = 6 u |
5x2 = 10 u |
When Fanny removed an equal number of purple marbles and yellow marbles, the difference between the number of purple marbles and yellow marbles at first and in the end remains the same.
LCM of 6 and 3 is 6.
Percentage of the marbles left in the box
=
1020 x 100%
= 12 x 100%
= 50%
Answer: 50%