#16 - Engineer: Thermophotovoltaic generators are devices

[taylorballou]

Hi,

Could you please confirm how to properly apply the assumption negation technique to answer choice E?
I narrowed down my contenders to C and E, but when I attempted to negate answer choice E, I got "There are no steel manufacturing plants that could greatly reduce their electricity bills only if they used some method of converting wasted heat or other energy from the steel manufacturing process into electricity." I thought that if no plant could save money with this process, then the conclusion in the stimulus would be incorrect. I underlined C as what I thought was the answer, but I think negating incorrectly confused me.

Thanks,

Taylor

[Eric Ockert]

Hey Taylor

Yeah, answer choice (E) is a doozy for the Assumption Negation Technique. Generally, when you see an answer written in the conditional like that, you negate the statement by showing that whatever that statement said was necessary is NOT actually necessary.

So here, answer choice (E) is effectively saying that some steel manufacturing plants can greatly reduce their electrical bills only by converting wasted heat into electricity. Before we get to the Assumption Negation Techinique, think about that. Do you really need there to be plants whose only way to greatly reduce is to make this conversion? Clearly not. Because (and here goes the Assumption Negation Technique) even if that was NOT the only way to do it, it could still be a very effective way to do it, and this argument would hold up just fine. So, even if what follows the "only if" clause is NOT required, the argument stands.

My colleague Jonathan had a great forum post with some other suggestions about logically negating statements a few months ago. You can check that out here for some more tips:

lsat/viewtopic.php?t=14903

Hope that helps!

[lilmissunshine]

Hello,

I figured that "primary" is the problem in (D) but I was a bit confused because the stimulus says "greatly reduce their electric bills". Does "greatly" require electricity energy to be the primary source of energy?

Many thanks!

[Adam Tyson]

Greatly reducing their electricity bills does not necessarily mean that electricity is their primary source of energy. I can take steps to greatly reduce my cable bill even if cable is not my primary source of entertainment, right? You were right to identify those words as being the main problem with answer choice D. Good job, lilmissunshine!

[flowskiferda]

This is a poorly written question imo: The stimulus says "if manufacturing plants could feed the heat they produce into generators..." It does not say anything about whether they could do so in a way that those generators could convert some of the heat into electricity. Perhaps you could feed the heat into those generators without them generating electricity because of some other issue. Thus it is still necessary to assume that if such heat is fed, it must be fed in such a way that the generators can actually turn it into electricity. I've seen correct answers on other LSAT questions be determined by similarly tiny issues in the wording, so how am I supposed to know that this question can't also be determined by such an issue?

[Beth Hayden]

Hi Flow,

There can be more than one necessary assumption for a stimulus! You're right that for this argument to work you also have to assume that the devices will actually work as intended in this specific situation, and that is actually something that I prephrased as well. Answer choice C is correct because it is one thing that you have to assume for the conclusion to be true, and the other four answer choices are not. It's fine if there are other things, which are not listed as answer choices, that are also necessary assumptions.

Hope that helps!
Beth

[emilyjmyer]

Hi!

I am still not understanding how choice C is correct.

I took "they would greatly reduce their electric bills, thereby saving money" to mean that by using this technology their electric bill would decrease. What does that have to do with covering the costs of the generators?

I am just confused because the stimulus says that they are going to reduce their electric bill. Maybe the generators are super expensive, but their electric bill is going to be $1 cheaper and they don't cover the cost of the generator.

Thanks!

[Adam Tyson]

You're right about the bill going down, emilyjmyer, but will they therefore be "saving money"? Not if the cost of the system is huge!

Here's an analogy: if you give me a million dollars, I will tutor you for 20 hours at a rate of $1 per hour. Your hourly tutoring rate will go way down compared to what you normally have to pay, but are you saving money? Not by a long shot! That million bucks you had to shell out means you would have been financially far better off if you had just paid the normal hourly rate, right?