Today we’ll tackle a problem from the June 2007 LSAT (you can download your own copy from LSAC). This is from section 3 and is a logical reasoning or “arguments” question:

Difficulty: Easy 

2. After replacing his old gas water heater with a new, pilotless, gas water heater that is rated as highly efficient, Jimmy’s gas bills increased.

Each of the following, if true, contributes to an explanation of the increase mentioned above EXCEPT:

(A) The new water heater uses a smaller percentage of the gas used by Jimmy’s household than did the old one.
(B) Shortly after the new water heater was installed, Jimmy’s uncle came to live with him, doubling the size of the household.
(C) After having done his laundry at a laundromat, Jimmy bought and started using a gas dryer when he replaced his water heater.
(D) Jimmy’s utility company raised the rates for gas consumption following installation of the new water heater.
(E) Unusually cold weather following installation of the new water heater resulted in heavy gas usage.

As always, our first task is to analyze the question. In this case the question is asking us to help explain the situation, or more accurately, we’re looking for what will help this argument make sense.

With EXCEPT/LEAST/NOT questions we always want to strike out EXCEPT/LEAST/NOT and instead treat the question like a yes/no question. 

Ok, so tackling the argument itself, we can see that what we need to be explaining away is the fact that Jimmy’s bill went up in spite of the fact that he installed a new, more efficient water heater. It might help to go ahead and think of some factors that would help, such as an increase in overall hot water use or an increase in the price of gas.With this question type we’ll need to think in a little bit more detail about each answer choice. A good question to ask ourselves for each of the answer choices would be, “could this help explain the increase?” 

Answer explanations after the jump.

A. Percentages, always be careful with percentages. This answer at first probably looks like a yes, but if we take it apart we see that using a smaller percentage of the overall gas used in the house doesn’t contribute to any explanation of how his bill went up. - N

B. The fact that the size of the household doubled doesn’t directly explain how his bill went up. However, this is a question asking if it could help explain it, so we’re allowed to make a small assumption if needed. In this case we could assume that doubling the size of the household might double the amount of gas-heated water used, thus helping explain the higher gas bill. - Y

C. An addition of a gas dryer is definitely going to account for some gas usage. So, we can say that it *could* explain the higher gas bill. - Y 

D. Raising the rates was one of the factors we thought up before we even got to the answers. Higher rates could definitely explain a higher bill in spite of lower usage. - Y 

E. Heavy gas usage is the key here. Obviously heavy usage could explain a higher bill, so this one is really a gimme. - Y

We have four yeses and one no,  so we know our odd-man-out is the right answer. Credited response is A 

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