10% of a 50% alcohol solution is replaced with water. From the resulting solution, again 10% is replaced with water. This step is repeated once more. What is the concentration of alcohol in the final solution obtained? Choose one:
A) 3%	B) 20%	C) 25%	D) 36%	E) 40%
Since the numbers in the answers are pretty far apart. I just simplified and rounded.   Alcohol = 50%   Total - 10% * 3 = 70%    .5 * .7= 
<gadget id="calculator"> .5 * .7</gadget>
<output>0.35</output>
.35 (so that means 70% of 50% of the total is 35%)   Answer: 36%) 36
<result>D</result>
10% of a 50% alcohol solution is replaced with water. From the resulting solution, again 10% is replaced with water. This step is repeated once more. What is the concentration of alcohol in the final solution obtained?