Mary replaced 20% of an 60% juice concentrate with water. Upon finding the resultant juice too sweet, she further replaced 30% of this solution with water, then fine tuned it by replacing 10% of that solution with water.
What is the final juice concentration Mary liked best?	Choose one.
A) 25.5%  B) 41.68%  C) 30.24%  D) 21%  E) 39.54%
The answer can be quickly calculated as: (60)(0.8)(0.7)(0.9)   How it works: By calculating how much juice is removed from an assumed 100 ml mixture, we can find out the final percentage.   In step 1, 20% of a 60% juice concentrate is replaced with water. With 100 ml of juice concentrate, this translates to removing 20% of juice, or rather keeping 80% of it. Hence, we multiply 60x0.8 = 48 ml.   In step 2, 30% of the solution is mixed with water. This translates to keeping 70% of the concentrate. Hence, 48x0.7 = 33.6 ml.   Finally in step 3, 10% of the solution is replaced with water. This means 90% of the concentrate remains. So, final amount of concentrate = 33.6x0.9 = 30.24 ml.   30.24 ml of concentrate in a 100 ml solution makes 30.24%   Answer: 30.24%
<result>C</result>
Mary replaced 20% of an 60% juice concentrate with water. Upon finding the resultant juice too sweet, she further replaced 30% of this solution with water, then fine tuned it by replacing 10% of that solution with water.
What is the final juice concentration Mary liked best?