PSLE Xuan had a box of grey balls and pink balls in the ratio 13 : 9. She removed an equal number of grey balls and pink balls from the box. The ratio of the number of grey balls and pink balls left in the box became 8 : 3. What percentage of the balls were left in the box?
|
Grey balls |
Pink balls |
Difference |
Total |
Before |
13x5 = 65 u |
9x5 = 45 u |
4x5 = 20 u |
22x5 = 110 u |
Change |
- 33 u |
- 33 u |
|
|
After |
8x4 = 32 u |
3x4 = 12 u |
5x4 = 20 u |
11x4 = 44 u |
When Xuan removed an equal number of grey balls and pink balls, the difference between the number of grey balls and pink balls at first and in the end remains the same.
LCM of 4 and 5 is 20.
Percentage of the balls left in the box
=
44110 x 100%
= 25 x 100%
= 40%
Answer: 40%