PSLE A box contained purple balls and grey balls. 40% of the balls were grey. After some silver balls were added to the box, 22% of the balls were grey. What percentage of the balls in the box were silver?
|
Grey |
Purple |
Silver |
Total |
Before |
2 u |
3 u |
|
5 u |
Change |
|
|
+ ? |
|
After |
22% |
33% |
|
100% |
40% =
40100 =
25 The number of grey balls remains unchanged.
2 u → 22%
1 u → 22% ÷ 2 = 11%
3 u → 3 x 11 = 33%
Percentage of the balls in the box that were silver
= 100% - 22% - 33%
= 45%
Answer(s): 45%