PSLE Xuan had a box of black beads and yellow beads in the ratio 13 : 7. She removed an equal number of black beads and yellow beads from the box. The ratio of the number of black beads and yellow beads left in the box became 5 : 1. What percentage of the beads were left in the box?
|
Black beads |
Yellow beads |
Difference |
Total |
Before |
13x2 = 26 u |
7x2 = 14 u |
6x2 = 12 u |
20x2 = 40 u |
Change |
- 11 u |
- 11 u |
|
|
After |
5x3 = 15 u |
1x3 = 3 u |
4x3 = 12 u |
6x3 = 18 u |
When Xuan removed an equal number of black beads and yellow beads, the difference between the number of black beads and yellow beads at first and in the end remains the same.
LCM of 6 and 4 is 12.
Percentage of the beads left in the box
=
1840 x 100%
= 920 x 100%
= 45%
Answer: 45%