PSLE A box contained gold marbles and purple marbles. 40% of the marbles were purple. After some black marbles were added to the box, 36% of the marbles were purple. What percentage of the marbles in the box were black?
|
Purple |
Gold |
Black |
Total |
Before |
2 u |
3 u |
|
5 u |
Change |
|
|
+ ? |
|
After |
36% |
54% |
|
100% |
40% =
40100 =
25 The number of purple marbles remains unchanged.
2 u → 36%
1 u → 36% ÷ 2 = 18%
3 u → 3 x 18 = 54%
Percentage of the marbles in the box that were black
= 100% - 36% - 54%
= 10%
Answer(s): 10%