PSLE Gwen had a box of white balls and yellow balls in the ratio 17 : 8. She removed an equal number of white balls and yellow balls from the box. The ratio of the number of white balls and yellow balls left in the box became 10 : 1. What percentage of the balls were left in the box?
|
White balls |
Yellow balls |
Difference |
Total |
Before |
17x1 = 17 u |
8x1 = 8 u |
9x1 = 9 u |
25x1 = 25 u |
Change |
- 7 u |
- 7 u |
|
|
After |
10x1 = 10 u |
1x1 = 1 u |
9x1 = 9 u |
11x1 = 11 u |
When Gwen removed an equal number of white balls and yellow balls, the difference between the number of white balls and yellow balls at first and in the end remains the same.
LCM of 9 and 9 is 9.
Percentage of the balls left in the box
=
1125 x 100%
= 1125 x 100%
= 44%
Answer: 44%