PSLE Tiffany had a box of red beads and gold beads in the ratio 17 : 9. She removed an equal number of red beads and gold beads from the box. The ratio of the number of red beads and gold beads left in the box became 9 : 4. What percentage of the beads were left in the box?
|
Red beads |
Gold beads |
Difference |
Total |
Before |
17x5 = 85 u |
9x5 = 45 u |
8x5 = 40 u |
26x5 = 130 u |
Change |
- 13 u |
- 13 u |
|
|
After |
9x8 = 72 u |
4x8 = 32 u |
5x8 = 40 u |
13x8 = 104 u |
When Tiffany removed an equal number of red beads and gold beads, the difference between the number of red beads and gold beads at first and in the end remains the same.
LCM of 8 and 5 is 40.
Percentage of the beads left in the box
=
104130 x 100%
= 45 x 100%
= 80%
Answer: 80%