PSLE A box contained purple marbles and grey marbles. 70% of the marbles were grey. After some white marbles were added to the box, 56% of the marbles were grey. What percentage of the marbles in the box were white?
|
Grey |
Purple |
White |
Total |
Before |
7 u |
3 u |
|
10 u |
Change |
|
|
+ ? |
|
After |
56% |
24% |
|
100% |
70% =
70100 =
710 The number of grey marbles remains unchanged.
7 u → 56%
1 u → 56% ÷ 7 = 8%
3 u → 3 x 8 = 24%
Percentage of the marbles in the box that were white
= 100% - 56% - 24%
= 20%
Answer(s): 20%