A can contains a mixture of two liquids A & B in ratio 7:5.A 9litre of mix is drawn out and can is filled with B. Te new ratio becomes 7:9. How many litres of A was contained by can initially
Nasty one...
Let's say the can contains x liters. So at first the a content is 7/12*x and the b content is 5/12*x.
After 9 liters are drawn, the ratio is maintained. So the a content is 7/12*(x-9) and b content is 5/12*(x-9).
After 9 liters of b are added, the b content is 5/12*(x-9)+9. The ratio then is 7:9 so you can also say the b content is 9/16*x (the can is full again so we use x).
So: 5/12*(x-9)+9 = 9/16x
...
x=36
The original a content was 7/12*x=7/12*36= 21 liters.
Am I right?
