PSLE Shiyun had a basket of blue beads and yellow beads in the ratio 17 : 8. She removed an equal number of blue beads and yellow beads from the basket. The ratio of the number of blue beads and yellow beads left in the basket became 7 : 3. What percentage of the beads were left in the basket?
|
Blue beads |
Yellow beads |
Difference |
Total |
Before |
17x4 = 68 u |
8x4 = 32 u |
9x4 = 36 u |
25x4 = 100 u |
Change |
- 5 u |
- 5 u |
|
|
After |
7x9 = 63 u |
3x9 = 27 u |
4x9 = 36 u |
10x9 = 90 u |
When Shiyun removed an equal number of blue beads and yellow beads, the difference between the number of blue beads and yellow beads at first and in the end remains the same.
LCM of 9 and 4 is 36.
Percentage of the beads left in the basket
=
90100 x 100%
= 910 x 100%
= 90%
Answer: 90%