PSLE Sabrina had a box of green marbles and red marbles in the ratio 13 : 7. She removed an equal number of green marbles and red marbles from the box. The ratio of the number of green marbles and red marbles left in the box became 8 : 3. What percentage of the marbles were left in the box?
|
Green marbles |
Red 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 Sabrina removed an equal number of green marbles and red marbles, the difference between the number of green marbles and red 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%