PSLE Emily had a box of grey marbles and brown marbles in the ratio 17 : 8. She removed an equal number of grey marbles and brown marbles from the box. The ratio of the number of grey marbles and brown marbles left in the box became 4 : 1. What percentage of the marbles were left in the box?
|
Grey marbles |
Brown marbles |
Difference |
Total |
Before |
17x1 = 17 u |
8x1 = 8 u |
9x1 = 9 u |
25x1 = 25 u |
Change |
- 5 u |
- 5 u |
|
|
After |
4x3 = 12 u |
1x3 = 3 u |
3x3 = 9 u |
5x3 = 15 u |
When Emily removed an equal number of grey marbles and brown marbles, the difference between the number of grey marbles and brown marbles at first and in the end remains the same.
LCM of 9 and 3 is 9.
Percentage of the marbles left in the box
=
1525 x 100%
= 35 x 100%
= 60%
Answer: 60%