A pharmacist has 4 quarts of a 15% solution of iodine. How much alcohol must be added to
reduce it to a 10% solution of iodine? Answers:	A) 1 quart	B) 2 quarts	C) 3 quarts	D) 4 quarts	E) 5 quarts
What’s being added? Hopefully, you said alcohol. Therefore our equation will look like this:   ALCOHOL + ALCOHOL = ALCOHOL   4 qts + x qts = (4 + x) qts   We start off with 4 quarts, add x quarts, then end up with (4 + x) quarts.   + =   4 x (4 + x)   Notice that you started with 4 quarts and added x quarts on the left side of the equation and you   ended up with (4 + x) on the other side. The parentheses indicate that it’s one container, Neato!   Of the original 4 quarts, 15% is iodine. Since we are doing the problem in terms of what we are   adding – alcohol, we must change 15% iodine solution to an 85% solution of alcohol. Let’s write   the equation.   .85(4) + x = .90(4x)   Where’d the .90 come from? Well, since I wanted to end up with a 10% solution of iodine, that   meant it must be a 90% solution of alcohol.   Multiplying both sides of the equation by the common denominator – 100, we have   85(4) + 100x = 90(4 + x)   340 + 100x = 360 + 90x   10x = 20   x = 2   You would have to add 2 quarts of alcohol to reduce the mixture to 10% iodine.   correct answer 2 quarts
<result>B</result>
A pharmacist has 4 quarts of a 15% solution of iodine. How much alcohol must be added to
reduce it to a 10% solution of iodine?