PSLE Linda had a bag of black balls and green balls in the ratio 17 : 8. She removed an equal number of black balls and green balls from the bag. The ratio of the number of black balls and green balls left in the bag became 5 : 2. What percentage of the balls were left in the bag?
|
Black balls |
Green balls |
Difference |
Total |
Before |
17x1 = 17 u |
8x1 = 8 u |
9x1 = 9 u |
25x1 = 25 u |
Change |
- 2 u |
- 2 u |
|
|
After |
5x3 = 15 u |
2x3 = 6 u |
3x3 = 9 u |
7x3 = 21 u |
When Linda removed an equal number of black balls and green balls, the difference between the number of black balls and green balls at first and in the end remains the same.
LCM of 9 and 3 is 9.
Percentage of the balls left in the bag
=
2125 x 100%
= 2125 x 100%
= 84%
Answer: 84%