Sukant2010 wrote:
Marvin’s behavior at the party last night is fascinating in that there is no evidence that he drank the entire container of punch despite the fact that he was the only person known to have been by the punchbowl between the time it was filled and the time it was observed to be empty. If Marvin had drunk the entire bowl, then some of the punch would inevitably have spilled on the tile, but I examined the tile carefully and found no evidence of spilled punch. Thus Marvin must not have drunk the entire punchbowl.
Which of the following, if true, most strengthens the argument?
A. Most large drinks that have been imbibed at parties result in significant spillage.
B. The person examining the tile for evidence of spilled punch has been able to detect such evidence in considerably more obscure, hidden places.
C. Marvin’s behavior at the party was observed for the first time by the examiner.
D. Many of the other telltale signs of a punchbowl’s being consumed were found.
E. At certain raucous parties like the party in question, some punchbowls are merely thrown out the window as part of a prank.
Let's analyze the argument.
Premises (assumed to be true):
- There is no evidence that Marvin drank the entire container of punch.
- He was the only person known to have been by the punch bowl between the time it was filled and the time it was observed to be empty. (Mind you, the premise doesn't say that he WAS the only person. It only says that he was the only person KNOWN to have been by the bowl. If someone else did go to the bowl, it is not known)
- If Marvin had drunk the entire bowl, then some of the punch would have spilled on the tile. (Taken to be a fact. If he had drunk the whole bowl, some punch would have spilled)
- I examined the tile carefully and found no evidence of spilled punch. (I examined and found no spillage is given. This doesn't mean there was no spillage. The point is that I found none)
Conclusion: Marvin must not have drunk the entire punch bowl.
There is one way in which we can prove beyond doubt that Marvin did not drink the entire punch bowl - if we can prove that there was certainly no spillage. 'I found no spillage' doesn't mean there was none. But if I am good at detecting spillage, it strengthens the conclusion that Marvin must not have drunk the entire punch bowl. It increases the probability that there is actually no spillage and hence the probability that Marvin did not drink the entire punch. Hence (B) is correct.
(E) At certain raucous parties like the party in question, some punchbowls are merely thrown out the window as part of a prank.
Option (E) provides an explanation of what could have happened to the punch (might have been thrown out - one of many possibilities) in case Marvin did not drink all of it. It doesn't strengthen the conclusion that Marvin did not drink the entire punch.