PSLE Pamela had a box of grey beads and green beads in the ratio 17 : 7. She removed an equal number of grey beads and green beads from the box. The ratio of the number of grey beads and green beads left in the box became 7 : 2. What percentage of the beads were left in the box?
|
Grey beads |
Green beads |
Difference |
Total |
Before |
17x1 = 17 u |
7x1 = 7 u |
10x1 = 10 u |
24x1 = 24 u |
Change |
- 3 u |
- 3 u |
|
|
After |
7x2 = 14 u |
2x2 = 4 u |
5x2 = 10 u |
9x2 = 18 u |
When Pamela removed an equal number of grey beads and green beads, the difference between the number of grey beads and green beads at first and in the end remains the same.
LCM of 10 and 5 is 10.
Percentage of the beads left in the box
=
1824 x 100%
= 34 x 100%
= 75%
Answer: 75%