PSLE A box contained yellow marbles and black marbles. 30% of the marbles were black. After some pink marbles were added to the box, 21% of the marbles were black. What percentage of the marbles in the box were pink?
|
Black |
Yellow |
Pink |
Total |
Before |
3 u |
7 u |
|
10 u |
Change |
|
|
+ ? |
|
After |
21% |
49% |
|
100% |
30% =
30100 =
310 The number of black marbles remains unchanged.
3 u → 21%
1 u → 21% ÷ 3 = 7%
7 u → 7 x 7 = 49%
Percentage of the marbles in the box that were pink
= 100% - 21% - 49%
= 30%
Answer(s): 30%