Question

how many quarts of water do you need to add to 40 quarts of 80 percent alcohol to get a solution of 10 percent alcohol?

Answer 1

\[ 40\cdot 0.2+x=(x+40)\cdot 0.9 \] Solve that.

Answer 2

vol of alcohol=40*80/100=32
vol of final soln such that alc=10%
means 320quarts
hence water to be added=320-40=280

Answer 3

Those two answers are equivalent.

Answer 4

fyi