Critical Reasoning

In response to mounting pubic concern, an airplane manufacturer implemented a program with the well-publicized goal of reducing by half the total yearly amount of hazardous waste generated by its passenger-jet division. When the program began in 1994, the division’s hazardous waste output was 90 pounds per production worker; last year it was
40 pounds per production worker. Clearly, therefore, charges that the manufacturer’s program has not met its goal are false.

Which of the following is an assumption on which the argument depends?
A. The amount of nonhazardous waste generated each year by the passenger-jet division has not increased significantly since 1994.
B. At least as many passenger jets were produced by the division last year as had been produced in 1994.
C. Since 1994, other divisions in the company have achieved reductions in hazardous waste output that are at least equal to that achieved in the passenger-jet division.
D. The average number of weekly hours per production worker in the passenger-jet division was not significantly greater last year than it was in 1994.
E. The number of production workers assigned to the passenger-jet division was not significantly less in 1994 than it was last year.

Looking at the question I thought it was an easy one to crack. Since the argument is about number of pounds/production worker, the argument has to assume something about the total number of production workers in 1994 should not be significantly less than in the previous year.

Say in 1994 - the number of workers is 10
Total hazardous waste = 1000 pounds then the number of pounds/worker is 100 pounds.

Last year the amount of waste = 1000 pounds and the number of workers are increased to 50 then the number of pounds/worker of the waste is 20 pounds.

So with this thought process I applied the Kaplan denial test and concluded that it weakens the argument. Thats why I choose E.

Obviously the answer was not E but B.

Stuart can you please explain how to differentiate between 2 choices that are very close (atleast in this case for me).

I would appreciate others input too.

Thanks.
Abhi

Your reasoning is perfect - are you sure that (e) isn't the correct choice?

(b) is outside the scope.

There is a difference in the assumption question and strengthen questions. Strengthen is opposite of Weaken. But the question asks about assumption. For a better understanding go through LSAT Critical reasoning bible.

As far as the question is concerned. Average = total amount / total number. Now the average can decrease either by a decrease in amount or increase in number. The reasoning you applied was basically concerned about "increase in number" and completely ignored "decrease in amount". Putting in the context of the question; what if the total number of passenger jets produced were half the amount of what it was in 1994?

The question is a classical average vs total question. The conclusion is reducing by half the total yearly amount and the premises only talk about average.

If I have to justify the question, I will say that you pay close attention to word significantly pointed out in option E. What if the number was less and not significantly less? B tells you that the "total amount" was equal whereas E allows (somewhat) less number to be acceptable. E is wrong because of "significantly".

By the way where did you get the question from. I will say that this is not a good question or a kind of question that you will see in GMAT...

Hi Stuart,

Yes the answer choice mentions B but I have heard that sometimes the answer choices are not the correct ones.

Its good to know atleast my reasoning was ok.

Thanks.
Abhi

Stuart Kovinsky wrote:Your reasoning is perfect - are you sure that (e) isn't the correct choice?

(b) is outside the scope.

Stuart
Why do you think that B is outside the scope? Its clearly mentions in the argument goal of reducing by half the total yearly amount of hazardous waste generated by its passenger-jet division. And if the passenger-jet division is not producing passenger jets, then how are they producing hazardous wastes?

simplyjat wrote:

Stuart Kovinsky wrote:Your reasoning is perfect - are you sure that (e) isn't the correct choice?

(b) is outside the scope.

Stuart
Why do you think that B is outside the scope? Its clearly mentions in the argument goal of reducing by half the total yearly amount of hazardous waste generated by its passenger-jet division. And if the passenger-jet division is not producing passenger jets, then how are they producing hazardous wastes?

We just care about achieving the goal. Nowhere does the argument mention how that goal is to be achieved. Perhaps the company is achieving it's goal by manufacturing fewer planes!

The answer to an assumption question is a statement that MUST be true in order for the argument to make sense. Let's look at (b) again:

(b) At least as many passenger jets were produced by the division last year as had been produced in 1994.

Does this HAVE to be true for the program to have been a success? What if last year the division produced 1 fewer plane - would that mean the program was a failure? Of course not. Since the denial of (b) doesn't disprove the argument, (b) isn't a MUST BE TRUE and therefore isn't an assumption.

This argument is a classic "numbers vs %s" scenario. We have a conclusion about numbers and evidence about rates. When this scenario shows up, the correct answer almost ALWAYS points out the discrepancy.

Honestly, I'd bet a big bunch of money that (e) is the right answer. Where is this question from?

The question is from the CR set I downloaded from scoretop and I am not too sure of its source.

-abhi

Stuart Kovinsky wrote:Does this HAVE to be true for the program to have been a success? What if last year the division produced 1 fewer plane - would that mean the program was a failure?

Take for example
Number of passenger jets produced in 1994 = 2
Amount of hazardous waste = 2X
Number of workers = Y

Number of passenger jets produced last year = 2 - 1 = 1
Amount of hazardous waste = 1X
Number of workers = Y

Clearly even when one less plane was produced last year, the average reduced from 2X/Y to X/Y. Which is clearly a 50% reduction.

Stuart Kovinsky wrote:Since the denial of (b) doesn't disprove the argument, (b) isn't a MUST BE TRUE and therefore isn't an assumption.

Before supporting denial test as an argument against B. Did you apply the denial test to E?. E says "significantly less" and denial will mean "not significantly less". With this I can easily replace B with E in your argument and still everything will hold true.
"Since the denial of (e) doesn't disprove the argument, (e) isn't a MUST BE TRUE and therefore isn't an assumption."
SIGNIFICANTLY is similar to MOST in logic, and thus means between 1% - 99%. Some will think that 1% is significantly less while others will think 99% is significantly less. And one should not assume a value other than these for MOST/SIGNIFICANTLY. And negating MOST/SIGNIFICANTLY gives back the same range from 99% to 1%.

And specifically I asked you why B was "out of scope" and not why B was "wrong".

simplyjat wrote:

Stuart Kovinsky wrote:Does this HAVE to be true for the program to have been a success? What if last year the division produced 1 fewer plane - would that mean the program was a failure?

Take for example
Number of passenger jets produced in 1994 = 2
Amount of hazardous waste = 2X
Number of workers = Y

Number of passenger jets produced last year = 2 - 1 = 1
Amount of hazardous waste = 1X
Number of workers = Y

Clearly even when one less plane was produced last year, the average reduced from 2X/Y to X/Y. Which is clearly a 50% reduction.

Stuart Kovinsky wrote:Since the denial of (b) doesn't disprove the argument, (b) isn't a MUST BE TRUE and therefore isn't an assumption.

Before supporting denial test as an argument against B. Did you apply the denial test to E?. E says "significantly less" and denial will mean "not significantly less". With this I can easily replace B with E in your argument and still everything will hold true.
"Since the denial of (e) doesn't disprove the argument, (e) isn't a MUST BE TRUE and therefore isn't an assumption."
SIGNIFICANTLY is similar to MOST in logic, and thus means between 1% - 99%. Some will think that 1% is significantly less while others will think 99% is significantly less. And one should not assume a value other than these for MOST/SIGNIFICANTLY. And negating MOST/SIGNIFICANTLY gives back the same range from 99% to 1%.

And specifically I asked you why B was "out of scope" and not why B was "wrong".

(b) is outside the scope because we don't care about HOW waste was reduced, we just care that it WAS reduced. If they reduced waste by closing the plant completely, then the program was a success.

Denying (e), we get:

It is not true that The number of production workers assigned to the passenger-jet division was not significantly less in 1994 than it was last year.

or, removing the double negative:

The number of production workers assigned to the passenger-jet division was significantly less in 1994 than it was last year.

Well, if the number of workers was significantly less in 1994, then that could certainly account for the ratio of waste/worker being a lot lower this year than it was in 1994. The denial of (e) provides an alternative explanation to the one theorized by the author. Therefore, (e) itself elminates that alternative.

Another classic GMAT argument type is causation. Here's another way we could summarize the author's reasoning:

(1) company put a program into place to reduce waste
(2) waste/worker was reduced
Therefore, the program was responsible for the reduction in waste/worker.

In abstract:

A happened, then B happened. Therefore, A caused B.

In every causal argument, the author is making 3 assumptions:

(1) causation isn't reversed (i.e. B didn't cause A)
(2) something else didn't cause B (e.g C didnt cause B)
(3) it's not just a coincidence that A and B happened together or in that order.

In a chronological causation argument, which we have in this question, option (1) doesn't make any sense. The most common issue that arises is (2) - another cause.

To weaken such an argument, we look for an alternative cause. To strengthen, we eliminate alternative causes, which is exactly what (e) does.

Stuart Kovinsky wrote:To weaken such an argument, we look for an alternative cause. To strengthen, we eliminate alternative causes, which is exactly what (e) does.

Stuart, you are not differentiating between assumption and strengthen question. Assumption question is not same as strengthen question.

And you are completely ignoring significantly, that is the biggest mistake.

You removed double negation the way you liked. It leave room for lot of other interpretations.

- The number of production workers assigned to the passenger-jet division was significantly less in 1994 than it was last year.
- The number of production workers assigned to the passenger-jet division was less in 1994 than it was last year.
- The number of production workers assigned to the passenger-jet division was equal in 1994 and in last year.
- The number of production workers assigned to the passenger-jet division was more in 1994 than it was last year.
- The number of production workers assigned to the passenger-jet division was significantly more in 1994 than it was last year.

All of the above interpretations are valid. But some lend support to the argument and some weaken the argument.

For any assumption question, the first assumption is "everything else remaining the same". And B is what states this specifically.

This question is also a classical example of "shell game" popular with standardized test takers. For better understanding of the concept, kindly refer to LSAT CR Bible.

This discussion really isn't progressing past the "he says/other he says" stage, so there's little point in continuing it.

I'm very familiar with the LSAT (I actually wrote the LSAT waaay back in 1988 and got a 48, the equivalent of an 800 on the GMAT, and I've been teaching the LSAT for *shudder* almost 20 years; in fact, I wrote Kaplan's current "advanced strengthening and weakening" lesson for our Stratosphere program). I'm very familiar with the difference between assumption and strengthen questions.

Of course, none of that means that I'm never wrong - I just don't happen to be wrong about this particular question.

Let me express my certainty that (e) should be correct as follows: if this question appeared on the actual exam, and (b) was the accredited choice, I'd personally hunt the question maker down and smack him or her upside the head with a herring until he or she admitted the mistake.

With regard to one point you make:

For any assumption question, the first assumption is "everything else remaining the same".

Let me offer an alternative with a key difference:

For any assumption question, the first assumption is "everything else RELEVANT remaining the same".

Again: the goal of the program is to reduce waste. We are given absolutely no hints as to how that goal is to be achieved. Therefore, any answer choices related to what was specifically done are going to be unevaluatable (a word I may have just made up) and, accordingly, outside the scope.

So, whether the company doubled or halved the number of planes it produced, we still do not know how that information relates to the program to reduce waste. The goal of the program was not "to reduce the amount of waste created by each plane" (in which case the number of planes produced would be relevant), the goal of the program was to reduce the amount of waste "generated by... the division".

We're getting far too involved in the specific details of this question. Remember, this exact question will never appear on test day. Let's review the important concepts (which will appear on test day):

(1) the GMAT loves to test #s vs. %s. When you see a stimulus that has actual numbers in the evidence and %s/rates/probabilities in the conclusion (or vice-versa), look for an answer that focuses on the disparity (usually by referring to the number of people involved in the activity).

(2) causation arguments are very common in CR stimuli. Learn to quickly recognize causation arguments and know the common assumption and ways to strengthen and weaken this classic argument type.

I am not sure why you are still sticking with E. You are not not considering the scope shift as well. Workers do not produce hazardous waste; process of manufacturing passenger-jets does.

I also am not interested in continuing this discussion any further, I have already wasted a lot of time explaining.

For the benefit of others hers is the definition of a shell game:

The LSAT makers have a variety of psychological tricks they use to entice test takers to select an answer choice. One of their favorites is one we call the Shell Game: an idea or concept is raised in the stimulus, and then a very similar idea appears in the answer choice, but the idea is changed just enough to be incorrect but still attractive. This trick is called the Shell Game because it abstractly resembles those street corner gambling games where a person hides a small object underneath one of three shells, and then scrambles them on a flat surface while a bettor tries to guess which shell the object is under (similar to three-card monte). The object of a Shell Game is to trick the bettor into guessing incorrectly by mixing up the shells so quickly and deceptively that the bettor mistakenly selects the wrong shell. The intent of the LSAT makers is the same.

Here is a sample question to illustrate shell game.

In an experiment, two-year-old boys and their fathers made pie dough together using rolling pins and other utensils. Each father-son pair used a rolling pin that was distinctively different from those used by the other father-son pairs, and each father repeated the phrase “rolling pin” each time his son used it. But when the children were asked to identify all of the rolling pins among a group of kitchen utensils that included several rolling pins, each child picked only the one that he had used.

Which one of the following inferences is most supported by the information above?
(A) The children did not grasp the function of a rolling pin.
(B) No two children understood the name “rolling pin” to apply to the same object.
(C) The children understood that all rolling pins have the same general shape.
(D) Each child was able to identify correctly only the utensils that he had used.
(E) The children were not able to distinguish the rolling pins they used from other rolling pins.

The “rolling pin” problem above is a famous question from the 1990s that lured many people to incorrectly select answer choice (D), a Shell Game answer. Answer choice (D) looks perfect at first glance, but the author never indicated that the children could identify only the utensils that they used. Rolling pins, yes; utensils, no. The correct answer choice is (B), which many test takers quickly pass over

I think its better we both take a second opinion and let someone else reply.

P.S. I tried googling the question but the OA is divided, there are some Es and some Bs. It seems to be one of those leaked GMAT question...

IMO E.

B is clearly IRRELEVANT and out of scope !

abhi75 wrote:In response to mounting pubic concern, an airplane manufacturer implemented a program with the well-publicized goal of reducing by half the total yearly amount of hazardous waste generated by its passenger-jet division. When the program began in 1994, the division’s hazardous waste output was 90 pounds per production worker; last year it was
40 pounds per production worker. Clearly, therefore, charges that the manufacturer’s program has not met its goal are false.

Which of the following is an assumption on which the argument depends?
A. The amount of nonhazardous waste generated each year by the passenger-jet division has not increased significantly since 1994.
B. At least as many passenger jets were produced by the division last year as had been produced in 1994.
C. Since 1994, other divisions in the company have achieved reductions in hazardous waste output that are at least equal to that achieved in the passenger-jet division.
D. The average number of weekly hours per production worker in the passenger-jet division was not significantly greater last year than it was in 1994.
E. The number of production workers assigned to the passenger-jet division was not significantly less in 1994 than it was last year.

Here we are trying to put a premise that logically takes us to the conclusion from the italics part of the stimulus.

IMO B is clearly irrelevant

IMO E is the best option among the 5 choices available.

IMO: E
the question states situation that company has decrease amount of waste in passenger jet division. from 90 to 40 per passanger jet
However, what if numbers of passenger jet produced increase ?

The total amount of waste from this division still remains if the productivity increase 2 times.