PSLE Sarah had a box of red marbles and pink marbles in the ratio 13 : 7. She removed an equal number of red marbles and pink marbles from the box. The ratio of the number of red marbles and pink marbles left in the box became 8 : 3. What percentage of the marbles were left in the box?
|
Red marbles |
Pink 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 Sarah removed an equal number of red marbles and pink marbles, the difference between the number of red 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 box
=
66100 x 100%
= 3350 x 100%
= 66%
Answer: 66%