PSLE Yoko had a basket of red marbles and blue marbles in the ratio 18 : 7. She removed an equal number of red marbles and blue marbles from the basket. The ratio of the number of red marbles and blue marbles left in the basket became 5 : 1. What percentage of the marbles were left in the basket?
|
Red marbles |
Blue marbles |
Difference |
Total |
Before |
18x4 = 72 u |
7x4 = 28 u |
11x4 = 44 u |
25x4 = 100 u |
Change |
- 17 u |
- 17 u |
|
|
After |
5x11 = 55 u |
1x11 = 11 u |
4x11 = 44 u |
6x11 = 66 u |
When Yoko removed an equal number of red marbles and blue marbles, the difference between the number of red marbles and blue marbles at first and in the end remains the same.
LCM of 11 and 4 is 44.
Percentage of the marbles left in the basket
=
66100 x 100%
= 3350 x 100%
= 66%
Answer: 66%