Bunuel
A butler stole wine from a cask that initially held a wine containing 12% alcohol. He then replaced the stolen wine with one that only contained 6% alcohol. As a result, the alcohol concentration in the wine within the cask decreased to 8%. What proportion of the original wine in the cask did the butler steal?
A. 1/3
B. 2/3
C. 3/4
D. 7/11
E. 9/13
We can use teeter - totter method (concept of weighted averages) to solve this question.
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Had the cask contained an equal volume of 12% alcohol and 6% alcohol then the concentration of alcohol in that cask would be 9%. However, the concentration of alcohol in the cask is 8%. Hence, we can infer that the cask has a greater quantity of 6% alcohol than of 12% alcohol.
The ratio of 12% Alcohol to 6% Alcohol in the cask with 8% alcohol = \(\frac{2}{4}\)
Therefore, the 8% cask has 2 parts of 6% alcohol and 1 part of 12% alcohol.
Hence, the butler stole 2 parts of the 12% wine, which the butler then replaced with the 6% wine, and, only 1 part of the 12% wine was left in the cask.
Proportion of the original wine that was stolen = \(\frac{2}{3}\)
Option B