PSLE Lynn had a basket of red balls and brown balls in the ratio 13 : 7. She removed an equal number of red balls and brown balls from the basket. The ratio of the number of red balls and brown balls left in the basket became 5 : 1. What percentage of the balls were left in the basket?
|
Red balls |
Brown balls |
Difference |
Total |
Before |
13x2 = 26 u |
7x2 = 14 u |
6x2 = 12 u |
20x2 = 40 u |
Change |
- 11 u |
- 11 u |
|
|
After |
5x3 = 15 u |
1x3 = 3 u |
4x3 = 12 u |
6x3 = 18 u |
When Lynn removed an equal number of red balls and brown balls, the difference between the number of red balls and brown balls at first and in the end remains the same.
LCM of 6 and 4 is 12.
Percentage of the balls left in the basket
=
1840 x 100%
= 920 x 100%
= 45%
Answer: 45%