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