PSLE Dana had a bag of grey beads and blue beads in the ratio 13 : 7. She removed an equal number of grey beads and blue beads from the bag. The ratio of the number of grey beads and blue beads left in the bag became 6 : 1. What percentage of the beads were left in the bag?
|
Grey beads |
Blue beads |
Difference |
Total |
Before |
13x5 = 65 u |
7x5 = 35 u |
6x5 = 30 u |
20x5 = 100 u |
Change |
- 29 u |
- 29 u |
|
|
After |
6x6 = 36 u |
1x6 = 6 u |
5x6 = 30 u |
7x6 = 42 u |
When Dana removed an equal number of grey beads and blue beads, the difference between the number of grey beads and blue beads at first and in the end remains the same.
LCM of 6 and 5 is 30.
Percentage of the beads left in the bag
=
42100 x 100%
= 2150 x 100%
= 42%
Answer: 42%