What strength of 20 ml alcohol should be added to 10ml of 50% alcohol to get an average strength of 20% alcohol. Answers
A) 0.5 %  B) 5 %  C) 50 %  D) 5.5 %  E) 0.05 %
20*x + 10*0.5 = (20 + 10)*0.2 --&gt; x = 0.05 = 5%.   Answer: 5 %.
<result>B</result>
What strength of 20 ml alcohol should be added to 10ml of 50% alcohol to get an average strength of 20% alcohol.