PSLE Joelle had a box of brown beads and red beads in the ratio 17 : 8. She removed an equal number of brown beads and red beads from the box. The ratio of the number of brown beads and red beads left in the box became 3 : 1. What percentage of the beads were left in the box?
|
Brown beads |
Red beads |
Difference |
Total |
Before |
17x2 = 34 u |
8x2 = 16 u |
9x2 = 18 u |
25x2 = 50 u |
Change |
- 7 u |
- 7 u |
|
|
After |
3x9 = 27 u |
1x9 = 9 u |
2x9 = 18 u |
4x9 = 36 u |
When Joelle removed an equal number of brown beads and red beads, the difference between the number of brown beads and red beads at first and in the end remains the same.
LCM of 9 and 2 is 18.
Percentage of the beads left in the box
=
3650 x 100%
= 1825 x 100%
= 72%
Answer: 72%