PSLE Esther had a box of silver beads and grey beads in the ratio 13 : 7. She removed an equal number of silver beads and grey beads from the box. The ratio of the number of silver beads and grey beads left in the box became 7 : 1. What percentage of the beads were left in the box?
|
Silver beads |
Grey beads |
Difference |
Total |
Before |
13x1 = 13 u |
7x1 = 7 u |
6x1 = 6 u |
20x1 = 20 u |
Change |
- 6 u |
- 6 u |
|
|
After |
7x1 = 7 u |
1x1 = 1 u |
6x1 = 6 u |
8x1 = 8 u |
When Esther removed an equal number of silver beads and grey beads, the difference between the number of silver beads and grey beads at first and in the end remains the same.
LCM of 6 and 6 is 6.
Percentage of the beads left in the box
=
820 x 100%
= 25 x 100%
= 40%
Answer: 40%