PSLE A box contained gold marbles and white marbles. 70% of the marbles were white. After some blue marbles were added to the box, 21% of the marbles were white. What percentage of the marbles in the box were blue?
|
White |
Gold |
Blue |
Total |
Before |
7 u |
3 u |
|
10 u |
Change |
|
|
+ ? |
|
After |
21% |
9% |
|
100% |
70% =
70100 =
710 The number of white 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 blue
= 100% - 21% - 9%
= 70%
Answer(s): 70%