PSLE Linda had a box of yellow beads and silver beads in the ratio 13 : 7. She removed an equal number of yellow beads and silver beads from the box. The ratio of the number of yellow beads and silver beads left in the box became 7 : 2. What percentage of the beads were left in the box?
|
Yellow beads |
Silver beads |
Difference |
Total |
Before |
13x5 = 65 u |
7x5 = 35 u |
6x5 = 30 u |
20x5 = 100 u |
Change |
- 23 u |
- 23 u |
|
|
After |
7x6 = 42 u |
2x6 = 12 u |
5x6 = 30 u |
9x6 = 54 u |
When Linda removed an equal number of yellow beads and silver beads, the difference between the number of yellow beads and silver beads at first and in the end remains the same.
LCM of 6 and 5 is 30.
Percentage of the beads left in the box
=
54100 x 100%
= 2750 x 100%
= 54%
Answer: 54%