PSLE Rachel had a box of green balls and gold balls in the ratio 17 : 7. She removed an equal number of green balls and gold balls from the box. The ratio of the number of green balls and gold balls left in the box became 7 : 2. What percentage of the balls were left in the box?
|
Green balls |
Gold balls |
Difference |
Total |
Before |
17x1 = 17 u |
7x1 = 7 u |
10x1 = 10 u |
24x1 = 24 u |
Change |
- 3 u |
- 3 u |
|
|
After |
7x2 = 14 u |
2x2 = 4 u |
5x2 = 10 u |
9x2 = 18 u |
When Rachel removed an equal number of green balls and gold balls, the difference between the number of green balls and gold balls at first and in the end remains the same.
LCM of 10 and 5 is 10.
Percentage of the balls left in the box
=
1824 x 100%
= 34 x 100%
= 75%
Answer: 75%