PSLE A box contained grey balls and green balls. 60% of the balls were green. After some black balls were added to the box, 36% of the balls were green. What percentage of the balls in the box were black?
|
Green |
Grey |
Black |
Total |
Before |
3 u |
2 u |
|
5 u |
Change |
|
|
+ ? |
|
After |
36% |
24% |
|
100% |
60% =
60100 =
35 The number of green balls remains unchanged.
3 u → 36%
1 u → 36% ÷ 3 = 12%
2 u → 2 x 12 = 24%
Percentage of the balls in the box that were black
= 100% - 36% - 24%
= 40%
Answer(s): 40%