PSLE Kathy had a basket of silver marbles and gold marbles in the ratio 13 : 7. She removed an equal number of silver marbles and gold marbles from the basket. The ratio of the number of silver marbles and gold marbles left in the basket became 3 : 1. What percentage of the marbles were left in the basket?
|
Silver marbles |
Gold marbles |
Difference |
Total |
Before |
13x1 = 13 u |
7x1 = 7 u |
6x1 = 6 u |
20x1 = 20 u |
Change |
- 4 u |
- 4 u |
|
|
After |
3x3 = 9 u |
1x3 = 3 u |
2x3 = 6 u |
4x3 = 12 u |
When Kathy removed an equal number of silver marbles and gold marbles, the difference between the number of silver marbles and gold marbles at first and in the end remains the same.
LCM of 6 and 2 is 6.
Percentage of the marbles left in the basket
=
1220 x 100%
= 35 x 100%
= 60%
Answer: 60%