PSLE A box contained pink balls and gold balls. 70% of the balls were gold. After some black balls were added to the box, 35% of the balls were gold. What percentage of the balls in the box were black?
|
Gold |
Pink |
Black |
Total |
Before |
7 u |
3 u |
|
10 u |
Change |
|
|
+ ? |
|
After |
35% |
15% |
|
100% |
70% =
70100 =
710 The number of gold balls remains unchanged.
7 u → 35%
1 u → 35% ÷ 7 = 5%
3 u → 3 x 5 = 15%
Percentage of the balls in the box that were black
= 100% - 35% - 15%
= 50%
Answer(s): 50%