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?

Question

2017 views around the world

You can reuse this answer
Creative Commons License

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%#