PSLE Zara had a bag of green balls and gold balls in the ratio 17 : 8. She removed an equal number of green balls and gold balls from the bag. The ratio of the number of green balls and gold balls left in the bag became 7 : 3. What percentage of the balls were left in the bag?
|
Green balls |
Gold balls |
Difference |
Total |
Before |
17x4 = 68 u |
8x4 = 32 u |
9x4 = 36 u |
25x4 = 100 u |
Change |
- 5 u |
- 5 u |
|
|
After |
7x9 = 63 u |
3x9 = 27 u |
4x9 = 36 u |
10x9 = 90 u |
When Zara removed an equal number of green balls and gold balls, the difference between the number of green balls and gold balls at first and in the end remains the same.
LCM of 9 and 4 is 36.
Percentage of the balls left in the bag
=
90100 x 100%
= 910 x 100%
= 90%
Answer: 90%