PSLE A box contained silver marbles and blue marbles. 70% of the marbles were blue. After some green marbles were added to the box, 21% of the marbles were blue. What percentage of the marbles in the box were green?
|
Blue |
Silver |
Green |
Total |
Before |
7 u |
3 u |
|
10 u |
Change |
|
|
+ ? |
|
After |
21% |
9% |
|
100% |
70% =
70100 =
710 The number of blue marbles remains unchanged.
7 u → 21%
1 u → 21% ÷ 7 = 3%
3 u → 3 x 3 = 9%
Percentage of the marbles in the box that were green
= 100% - 21% - 9%
= 70%
Answer(s): 70%