PSLE Diana had a basket of red balls and yellow balls in the ratio 18 : 7. She removed an equal number of red balls and yellow balls from the basket. The ratio of the number of red balls and yellow balls left in the basket became 3 : 1. What percentage of the balls were left in the basket?
|
Red balls |
Yellow balls |
Difference |
Total |
Before |
18x2 = 36 u |
7x2 = 14 u |
11x2 = 22 u |
25x2 = 50 u |
Change |
- 3 u |
- 3 u |
|
|
After |
3x11 = 33 u |
1x11 = 11 u |
2x11 = 22 u |
4x11 = 44 u |
When Diana removed an equal number of red balls and yellow balls, the difference between the number of red balls and yellow balls at first and in the end remains the same.
LCM of 11 and 2 is 22.
Percentage of the balls left in the basket
=
4450 x 100%
= 2225 x 100%
= 88%
Answer: 88%