PSLE A box contained black marbles and grey marbles. 40% of the marbles were grey. After some green marbles were added to the box, 18% of the marbles were grey. What percentage of the marbles in the box were green?
|
Grey |
Black |
Green |
Total |
Before |
2 u |
3 u |
|
5 u |
Change |
|
|
+ ? |
|
After |
18% |
27% |
|
100% |
40% =
40100 =
25 The number of grey marbles remains unchanged.
2 u → 18%
1 u → 18% ÷ 2 = 9%
3 u → 3 x 9 = 27%
Percentage of the marbles in the box that were green
= 100% - 18% - 27%
= 55%
Answer(s): 55%