PSLE Cathy had a basket of yellow marbles and gold marbles in the ratio 13 : 7. She removed an equal number of yellow marbles and gold marbles from the basket. The ratio of the number of yellow marbles and gold marbles left in the basket became 8 : 3. What percentage of the marbles were left in the basket?
|
Yellow marbles |
Gold marbles |
Difference |
Total |
Before |
13x5 = 65 u |
7x5 = 35 u |
6x5 = 30 u |
20x5 = 100 u |
Change |
- 17 u |
- 17 u |
|
|
After |
8x6 = 48 u |
3x6 = 18 u |
5x6 = 30 u |
11x6 = 66 u |
When Cathy removed an equal number of yellow marbles and gold marbles, the difference between the number of yellow marbles and gold marbles at first and in the end remains the same.
LCM of 6 and 5 is 30.
Percentage of the marbles left in the basket
=
66100 x 100%
= 3350 x 100%
= 66%
Answer: 66%