PSLE Sarah had a basket of grey balls and green balls in the ratio 16 : 9. She removed an equal number of grey balls and green balls from the basket. The ratio of the number of grey balls and green balls left in the basket became 5 : 1. What percentage of the balls were left in the basket?
|
Grey balls |
Green balls |
Difference |
Total |
Before |
16x4 = 64 u |
9x4 = 36 u |
7x4 = 28 u |
25x4 = 100 u |
Change |
- 29 u |
- 29 u |
|
|
After |
5x7 = 35 u |
1x7 = 7 u |
4x7 = 28 u |
6x7 = 42 u |
When Sarah removed an equal number of grey balls and green balls, the difference between the number of grey balls and green balls at first and in the end remains the same.
LCM of 7 and 4 is 28.
Percentage of the balls left in the basket
=
42100 x 100%
= 2150 x 100%
= 42%
Answer: 42%