PSLE Jade had a basket of yellow balls and red balls in the ratio 16 : 9. She removed an equal number of yellow balls and red balls from the basket. The ratio of the number of yellow balls and red balls left in the basket became 7 : 3. What percentage of the balls were left in the basket?
|
Yellow balls |
Red balls |
Difference |
Total |
Before |
16x4 = 64 u |
9x4 = 36 u |
7x4 = 28 u |
25x4 = 100 u |
Change |
- 15 u |
- 15 u |
|
|
After |
7x7 = 49 u |
3x7 = 21 u |
4x7 = 28 u |
10x7 = 70 u |
When Jade removed an equal number of yellow balls and red balls, the difference between the number of yellow balls and red 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
=
70100 x 100%
= 710 x 100%
= 70%
Answer: 70%