PSLE Kimberly had a box of silver beads and grey beads in the ratio 18 : 7. She removed an equal number of silver beads and grey beads from the box. The ratio of the number of silver beads and grey beads left in the box became 9 : 1. What percentage of the beads were left in the box?
|
Silver beads |
Grey 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 Kimberly removed an equal number of silver beads and grey beads, the difference between the number of silver beads and grey beads at first and in the end remains the same.
LCM of 11 and 8 is 88.
Percentage of the beads left in the box
=
110200 x 100%
= 1120 x 100%
= 55%
Answer: 55%