PSLE Lynn had a box of red beads and silver beads in the ratio 16 : 9. She removed an equal number of red beads and silver beads from the box. The ratio of the number of red beads and silver beads left in the box became 3 : 1. What percentage of the beads were left in the box?
|
Red beads |
Silver beads |
Difference |
Total |
Before |
16x2 = 32 u |
9x2 = 18 u |
7x2 = 14 u |
25x2 = 50 u |
Change |
- 11 u |
- 11 u |
|
|
After |
3x7 = 21 u |
1x7 = 7 u |
2x7 = 14 u |
4x7 = 28 u |
When Lynn removed an equal number of red beads and silver beads, the difference between the number of red beads and silver beads at first and in the end remains the same.
LCM of 7 and 2 is 14.
Percentage of the beads left in the box
=
2850 x 100%
= 1425 x 100%
= 56%
Answer: 56%