PSLE A box contained blue beads and purple beads. 30% of the beads were purple. After some black beads were added to the box, 27% of the beads were purple. What percentage of the beads in the box were black?
|
Purple |
Blue |
Black |
Total |
Before |
3 u |
7 u |
|
10 u |
Change |
|
|
+ ? |
|
After |
27% |
63% |
|
100% |
30% =
30100 =
310 The number of purple beads remains unchanged.
3 u → 27%
1 u → 27% ÷ 3 = 9%
7 u → 7 x 9 = 63%
Percentage of the beads in the box that were black
= 100% - 27% - 63%
= 10%
Answer(s): 10%