Question

A pot is filled with alcohol. 80% of alcohol is replaced by the same quantity of water. This process is done three times. Then find the percentage of alcohol in this mixture of alcohol and water: a) 51.2% b) 29% c) 38% d) 49%

Answer 1

0.8% of the given mixture is alcohol. None of the options given are correct.

To simplify the problem, assume 100 gm alcohol is taken.  

First time: 80% of 100 gm is 80 gm. So, alcohol content is now 100 – 80 = 20 gm out of 100 gm.

Second time: 80% of 20 gm is 16 gm. So, alcohol content is now 20 - 16 = 4 gm out of 100 gm.

Third time: 80% of 4 gm is 3.2 gm. So, alcohol content is now 4 - 3.2 = 0.8 gm out of 100 gm.

0.8 out of 100 gm is equal to 0.8% of the mixture.

Hence, percentage of alcohol in the mixture is 0.8%.

Answer 2

alcohol is 0.8 percent