how many liters of water must be added to 30 liters of a 20% alcohol solution to dilute it to a 15% solution?

Answer 1

you are diluteing it 20/15=1.333 times

Add one part solution, .333333 water.

This means if one part is 30 liters, add 10 liters water.

Check: .2*30/(40+10)=6/40=.15 or 15 percent.