PSLE Xylia had a box of gold marbles and white marbles in the ratio 13 : 7. She removed an equal number of gold marbles and white marbles from the box. The ratio of the number of gold marbles and white marbles left in the box became 8 : 3. What percentage of the marbles were left in the box?
|
Gold marbles |
White 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 Xylia removed an equal number of gold marbles and white marbles, the difference between the number of gold marbles and white marbles at first and in the end remains the same.
LCM of 6 and 5 is 30.
Percentage of the marbles left in the box
=
66100 x 100%
= 3350 x 100%
= 66%
Answer: 66%