A 40-liter barrel is full of wine which contains 8% of alcohol. 10 liters of the wine is drawn off and replaced by water. What percentage of alcohol is the mixture?

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Answer 1 · 2018-06-10T18:26:08

#6%#

Lets firstly find the #8%# of alcohol in the 40-litre barrel.

#40*0.08=3.2#

That is 3.2 litres worth of alcohol in the 40-litre barrel.

Then 10 litres of wine is drawn and replaced by water. Here we find the alcohol percentage in 10 litres of the wine:

#10*0.08=0.8# litres (which is also 1/4 of alcohol in the 40-litre barrel).

So take this value away from the original of 3.2 litres:

#3.2-0.8= 2.4 # litres.

To find the percentage of alcohol in the 40-litre barrel:

#40-2.4=37.6#
#((40-37.6)/40)*100= 6%#