PSLE A box contained yellow beads and black beads. 70% of the beads were black. After some silver beads were added to the box, 49% of the beads were black. What percentage of the beads in the box were silver?
|
Black |
Yellow |
Silver |
Total |
Before |
7 u |
3 u |
|
10 u |
Change |
|
|
+ ? |
|
After |
49% |
21% |
|
100% |
70% =
70100 =
710 The number of black beads remains unchanged.
7 u → 49%
1 u → 49% ÷ 7 = 7%
3 u → 3 x 7 = 21%
Percentage of the beads in the box that were silver
= 100% - 49% - 21%
= 30%
Answer(s): 30%