PSLE Esther had a basket of blue marbles and red marbles in the ratio 13 : 7. She removed an equal number of blue marbles and red marbles from the basket. The ratio of the number of blue marbles and red marbles left in the basket became 6 : 1. What percentage of the marbles were left in the basket?
|
Blue marbles |
Red marbles |
Difference |
Total |
Before |
13x5 = 65 u |
7x5 = 35 u |
6x5 = 30 u |
20x5 = 100 u |
Change |
- 29 u |
- 29 u |
|
|
After |
6x6 = 36 u |
1x6 = 6 u |
5x6 = 30 u |
7x6 = 42 u |
When Esther removed an equal number of blue marbles and red marbles, the difference between the number of blue marbles and red marbles at first and in the end remains the same.
LCM of 6 and 5 is 30.
Percentage of the marbles left in the basket
=
42100 x 100%
= 2150 x 100%
= 42%
Answer: 42%