In response to mounting public concern, an airplane

I had gone for D too.



The above argument is based on the number of production workers. So I suppose we should choose an answer which counts the number of production workers and not the amount of nonhazardous waste/ no.of passenger jets/ average weekly hours of a single worker.

Only E does that.

I went for E straight...since we are interested in total yearly amount of hazardous waste generated by its passenger-jet division and the premise given is in terms of waste generated per production worker...We can straight forward see the gap in which the no of persons which will effect the total output are assumed to be constant/same by the author.So only option E address this gap.


Also option D takes into consideration the no of hrs per week which will in no way affect the output/person as no such relation is mentioned anywhere in the passage.

Hope its clear!!!

hi Rock ..
If you go with B you are assuming that production of waste is directly proportional to number of jets produced ...However this assumption is not substantiated in the argument ( not even mentioned)....

waster per worker ( as per the question ) ==
total waste/ number of workers ...( and not number of jets produced / number of workers )

i picked E
regards

Initially I went with D. After seeing the OA as E, I spent lot of time understanding this and came up with the following reasoning.

There are 3 possibilities why the amount of hazardous waste per worker came down:

1. Company produced less no. of planes
2. Company hired more no. of employees.
3. Company followed the new process.

As the question is asking about the assumption, we need to take the conclusion for granted, which means the reason for the reduction in the waste per worker is improvement in the process.

Now this improvement in the process also can happen in 3 situations:
1. Process improved at the time when company produced more no. of planes
2. Process improved at the time when company hired less no of employees
3. Process improved when company maintained counts of employees and produced planes are constant.
Note: we can ignore counter cases like producing less no. of planes and hiring more no of employees because in those cases, even if the process is not improved, there is a high chance that amount of waste per worker comes down.

Now in answer choices...

B comes as a contender for case 1. But it fails when we go for the extreme case (B says at least same no. of planes were produced. In the worst case, it could have produced high no. of planes. In such a case, still take the conclusion for granted, we should have a substantial information in the argument but that is missing)

E comes as a contender for case 2. Even in the worst case it stands. (worst case implies no. of employees in 1994 and now is same and it clearly tells that the conclusion is correct.)

D also comes as a contender, but we can not evaluate with the given info as we did in B & E.

conclusion : charges that the manufacturer's program has not met its goal are false
premise :the division's hazardous waste output was 90 pounds per production worker; last year it was 40 pounds per production worker
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.

hazardous waste output per production worker = total amount of hazardous waste/ total number of people

so probable assumptions could be

1. total number of people has remain constant and total amt of hazardous waste is reduced to half .


now lets have a look at the options :

a)A. The amount of nonhazardous waste generated each year by the passenger-jet division has not increased significantly since 1994. company is planning to reduce the total amt of mat by half, however from this statement we could only ascertain that amt has not risen significantly. may be no of people have also halved n tht is the reason for reduction frm 0.9 to 0.4.

B. At least as many passenger jets were produced by the division last year as had been produced in 1994. out of scope... we are taking about hazardous waste amount per pessenger .... same number of jet does not let us ascertain that ratio could have come down. Probably same no of units produce more hazardous material

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. out of scope we are only taking abt hazardous material reduction by 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. again we are not concerned abt no of hr each workers put in. only parameter tht could influence
hazardous waste amount per passenger is either no of people or total amt

E. The number of production workers assigned to the passenger-jet division was not significantly less in 1994 than it was last year. hazardous waste amount per passenger from 0.9 to 0.4 , with total no remaining constant translate to reduction in more thn half of hazardous waste amount . hence correct answer

The question says that the airplane manufacturer reduced the hazardous waste output from 90 tonnes/worker to 40 tonnes/worker. How can this ratio (tonnes/worker) be decreased? It can be decreased if the actual emissions decrease but the number of workers remain the same or decreases (i.e. the numerator decreases in greater proportion to the denominator). Alternatively, it can be decreased if the number of workers goes up, but the emissions stay the same or increase less in proportion to the increase in the number of workers (i.e. the denominator increases in greater proportion to the numerator).

In the first case (emissions going down), the airline manufacturer would have actually reduced emissions. In the second (number of employees going up), the ratio would decrease without the emissions necessarily going down. Therefore, for this to represent a true decrease in emissions, we will have to assume that the number of employees did not go up.

Option (E) expresses this most clearly and is therefore the best choice.

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.

Wrong: nonhazardous waste is irrelevant.

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

Wrong:
Number of passenger jets is irrelevant

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.

Wrong:
Other divisions are out of scope.

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.

Wrong: Weekly hours is irrelevant.

E. The number of production workers assigned to the passenger-jet division was not significantly less in 1994 than it was last year.
Correct:
If the number of workers has increased and the total waste remained the same, then the waste per person would decrease, but the total waste would remain the same.

In response to mounting public 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.

Type - assumption
Boil it down - Waste output per worker has decreased from 90 to 40 . Hence, charges that manufacturer has not met its goal are false.
Pre-thinking -
Amount of water per worker has gone down by over 50%
- decrease in pounds of waste
- increase in number of workers
If the number of workers has increased from 1994 till last year , then argument will fall apart


E. The number of production workers assigned to the passenger-jet division was not significantly less in 1994 than it was last year. Correct
Answer E

The only assumption that justifies the conclusion is that total number of workers hasn't substantially changed since we're talking about the waste per worker:
1994:
№ of W = 100
Waste/worker = 90
Total waste = 9000
nowdays:
№ of W = 225
Waste/worker = 40
Total waste = 9000

So, author's point to be valid, we need to seek for assumption that the number of workers has retained at roughly the same level as it was in 1994.
Answer E gives us that lacking assumption, and when negated it utterly shutters the conclusion to pieces.

Conclusion: charges that the manufacturer's program has not met its goal are false
Prethink: how do we know the number of people didn’t significantly increase? So the denominator is bigger but the numerator stayed the same (or maybe even slightly increased), resulting in a smaller number.

A. The amount of nonhazardous waste generated each year by the passenger-jet division has not increased significantly since 1994.
Incorrect focus: this doesn’t have to be true. We want to hit on the point of the denominator (i.e., the number of people), NOT the numerator (i.e., the amount of waste).

B. At least as many passenger jets were produced by the division last year as had been produced in 1994.
Out of scope – We’re concerned about the waste per production WORKER. Not the number of planes produced. If anything, this could weaken the claim. The average output would be consistent, keeping all things equal or increase (if the passenger jets produced increased b/c more waste)

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.
Out of scope – We’re not concerned about OTHER divisions.

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.
Out of scope – we don’t care about the average number of weekly hours PER production worker. It could increase or decrease, and it would not affect the argument. We want to know if the actual NUMBER of production workers increased.

E. The number of production workers assigned to the passenger-jet division was not significantly less in 1994 than it was last year.
Bingo. Shows that the denominator didn’t significantly increase between 1994 and last year. Thus, this must be an assumption. Otherwise, it would shatter the argument.

Goal: To reduce by half the total yearly amount of hazardous waste generated by its passenger-jet division
Facts: In 1994, waste output = 90 lbs / worker and Last year, waste output = 40 lbs / worker
Conclusion: Manufacturer achieved the goal.

Negate (A)
(A) The amount of nonhazardous waste generated each year by the passenger-jet division HAS increased significantly since 1994. - Even if this is true, that increased amount of waste could've been reduced by the manufacturer. We just dont have more information. Doesn't break the conclusion

(B) At least as many passenger jets were produced by the division last year as had been produced in 1994. - We are talking about the waste produced by that division and NOT the jets produced. There is no relationship given between jets produced and waste produced from it.

(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. - This is just irrelevant. We simply dont care about other divisions.

Negate (D) & (E)
(D) The average number of weekly hours per production worker in the passenger-jet division WAS significantly greater last year than it was in 1994. -
We are not given any relationship between weekly hours of production worker and output generated by each worker.
So, just because no. of hours were more last year does NOT mean that the waste generated will be more.
So, even if this is true, that increased amount of waste could've been reduced by the manufacturer.

(E) The number of production workers assigned to the passenger-jet division WAS significantly less in 1994 than it was last year. - Consider the following example
1994 , workers = 20, Waste = 90 lbs, Total waste = 1800 lbs
Last year, workers = 80, Waste = 40 lbs, Total waste = 3200 lbs
Certainly didn't reduce half the waste now, did he?

GMATNinja
in general, if the argument statement provided did not specify a certain type of information, then we could not use the information in the answer choices as the basis of evaluation? in other words, I was thinking that what if the number of hours a worker put in is proportional to the waste produced and all else equal? same total worker but less hours per day and less total waste.
I recalled there was a post about common sense application in CR, and I thought this assumption I made may be in the grey area. I guess just gotta avoid grey answers and choose the best..

On many CR questions, you're looking for the "best" option out of the five answer choices. For example, if the question reads, "which of the following, if true, most strengthens the argument?" or "Which of the following would be most helpful in evaluating the argument?" or "Which of the following best expresses the conclusion of the argument as a whole?"

Because these questions use words like "most" or "best," you're really just looking for the answer choice that is better than all of the other options.

That's not the case for this particular question. Here, we're asked to find which answer choice "is an assumption on which the argument depends." So, we're not looking for the most-assumption-y option, we're looking for the one option that fulfills a particular role. One of the answer choices MUST be true in order for the argument to hold, while the other ones don't necessarily have to be true in order for the argument to hold.

Before we dive into the answer choices, here's a look at the argument:

• The author gives us some background information: "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."
• The author concludes that: "charges that the manufacturer's program has not met its goal are false."
• The author supports this conclusion with a fact: "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."

Overall, the author believes that the airplane manufacturer HAS met its goal. That goal was to reduce by half the hazardous waste from the passenger-jet division. The author's evidence for this belief is that the waste output per worker declined from 90 pounds to 40 pounds.

Here, you can begin to see a gap in the argument: the author thinks that overall waste production must be down by 50% because waste production per worker is down by over 50%.

So, which answer choice is an assumption on which the argument depends?

The evidence is given in pounds of waste produced per worker. So, whether a worker works 1 hour each week or 40 hours each week, he/she still only counts as one worker in the equation.

Let's say that workers DO work a lot more hours now than they did in 1994. The author's argument is still fine -- perhaps this waste management program is amazingly effective, and even though workers are putting in a ton of extra hours and producing a bunch of planes, the overall waste is way down.

We have no way of assessing how each worker's hours impact the number of workers or the overall waste, which are the two factors at play in the argument.

Overall, (D) doesn't HAVE to be true in order for the argument to hold, so you can eliminate (D).


The author says that overall waste is down because waste per worker is down.

But wait a minute -- what if there are just way more workers now than there used to be? Then overall waste could be exactly the same, even as waste per worker goes down. This completely destroys the author's argument, because it invalidates the evidence that he/she presented.

So, for the author's argument to hold any water, it MUST be true that the number of workers in 1994 was not significantly less than the number of workers now.

(E) must be true, so (E) is the assumption on which the argument depends.

I hope that helps!

in E] does the word 'significant' important here.

will this choice be dicey in the absense of it

Technically yes. (If the number of hours per worker were only marginally greater, the integrity of the argument wouldn't be compromised.)

Accordingly, this choice nicely illustrates the careful attention to detail with which GMAC's correct answers are worded.





Hypothetically yes, but you won't see choices like that from GMAC. The wrong answers will be WRONG—not "going the right way but too weak".

like option D] I at times see the following statement structire

''The number of employees assigned to the manufacturing department was not significantly higher three years ago than it is at present''


-Earlier I used to read this as- The number of employees was marginally higher 3 years ago.

But then someone told me that the real inference is :

a] The number 3 years ago is same as at present
b] The number 3 years ago is lower than at present


Is that true? Could you please share why such is the case. I hope you understand my confusion here.

Could actually be any of those three. "Not significantly higher" means lower OR the same OR higher by a negligible amount.

Remember the context here: This is an assumption question. Many assumptions are in place simply to rule out possibilities that would otherwise break the argument.
So, if an argument would break if some quantity WERE significantly higher, then the argument has to assume "not significantly higher" for that quantity.

This isn't the quant section, so you won't need to go through all three of the possibilities above. For potential *assumptions* that are negative statements, just use the 'negation method': Negate the potential assumption (which in these cases will turn it from a negative statement back into an affirmative one), and check whether that affirmative statement breaks the logic of the argument.