PSLE Nicole had a basket of grey balls and blue balls in the ratio 13 : 7. She removed an equal number of grey balls and blue balls from the basket. The ratio of the number of grey balls and blue balls left in the basket became 8 : 3. What percentage of the balls were left in the basket?
|
Grey balls |
Blue balls |
Difference |
Total |
Before |
13x5 = 65 u |
7x5 = 35 u |
6x5 = 30 u |
20x5 = 100 u |
Change |
- 17 u |
- 17 u |
|
|
After |
8x6 = 48 u |
3x6 = 18 u |
5x6 = 30 u |
11x6 = 66 u |
When Nicole removed an equal number of grey balls and blue balls, the difference between the number of grey balls and blue balls at first and in the end remains the same.
LCM of 6 and 5 is 30.
Percentage of the balls left in the basket
=
66100 x 100%
= 3350 x 100%
= 66%
Answer: 66%