PSLE Dana had a bag of pink beads and black beads in the ratio 18 : 7. She removed an equal number of pink beads and black beads from the bag. The ratio of the number of pink beads and black beads left in the bag became 9 : 1. What percentage of the beads were left in the bag?
|
Pink beads |
Black beads |
Difference |
Total |
Before |
18x8 = 144 u |
7x8 = 56 u |
11x8 = 88 u |
25x8 = 200 u |
Change |
- 45 u |
- 45 u |
|
|
After |
9x11 = 99 u |
1x11 = 11 u |
8x11 = 88 u |
10x11 = 110 u |
When Dana removed an equal number of pink beads and black beads, the difference between the number of pink beads and black beads at first and in the end remains the same.
LCM of 11 and 8 is 88.
Percentage of the beads left in the bag
=
110200 x 100%
= 1120 x 100%
= 55%
Answer: 55%