That the application of new technology can increase the productivity o

Question

That the application of new technology can increase the productivity of existing coal mines is demonstrated by the case of Tribnia's coal industry. Coal output per miner in Tribnia is double what it was five years ago, even though no new mines have opened.

Which of the following can be properly concluded from the statement about coal output per miner in the passage?

Which of the following can be properly concluded from the statement about coal output per miner in the passage?

(A) If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia's total coal production has doubled in that period of time.

(B) Any individual Tribnian coal mine that achieved an increase in overall ouput in the past five years has also experienced an increase in output per miner.

(C) If any new coal mines had opened in Tribnia in the past five years, then the increase in output per miner would have been even greater than it actually was.

(D) If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine's overall output has declined or remained constant.

(E) In Tribnia the cost of producing a given quantity of coal has declined over the past five years.

ncp · Accepted Answer

Five Years ago,

Coal output per miner(x) = Total Coal Quantity(x)/Total no. of miners(x)

Today, 

Coal output per miner(today)=2*Coal output per miner(x)
 =2*Total Coal Quantity(x)/Total no. of miners(x)

Equating,

Total coal quantity(today)/Total no.of miners(today)=2*Total Coal Quantity(x)/Total no. of miners(x)

If Total no.of miners(today)= Total no.of miners(x), then 
Total coal quantity(today) = 2*Total Coal Quantity(x)

This is the same as A->If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia's total coal production has doubled in that period of time. 

So, my pick is A.

tennis1ball · Answer

I prefer A.


A. Very straight forward logic.

B. You can't deduce this, reversely based on the logic.

C. The question is not talking about NEW mines.

D and E are irrelevant.

khaos · Answer

Production = average output * no. of miners

Therefore, if no. of miners is constant, then:

2*production = 2*average output * no. of miners

Answer =  A

Mishari · Answer

X: increase in technology applications for mines
Y: increase in mine production 

The argument claims that X --> Y

we conclude that 
Y --/--> X
Z --/--> Y where Z is any other variable or change

Answer (A) provides that Z, change in the number of miners, remained constant during the period. Because Y is a rate  , then a change in the number of miners   can cause a change in the coal output per miner  .

Thus,  answer A  provides that Z --/--> Y

RGM · Answer

I'm with A. B and D discuss individual coal mines and what their impact would be if those variables changed - out of scope. E discusses costs - out of scope. C - just because a new mine opened does not mean there would be greater productivity as a whole. The new mine could very well be a wasted venture, and could drag down output per miner.

dwivedys · Answer

Dear RGM - It's a great analysis you've shown - only if you could also tell how did you so definitively conclude that because B and D were discussing INDIVIDUAL coal mines hence they were out of scope?

RGM · Answer

I considered them as out of scope just because the premise does not say anything about the individual coal mines.

B states - "Any individual Tribnian coal mine that achieved an increase in overall output in the past five years has also experienced an increase in output per miner." One case might be that a particular mine decided to increase manpower to increase yield. If this is the case, then there is no increase in output per miner. The premise did not say that the number of workers remained constant for all individual mines.

D states - "If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine’s overall output has declined or remained constant." This is like the reverse of B. If the premise said that the number of workers remained constant for all individual mines, we can conclude that if the output per miner decreased, the overall output decreased for that mine.

Some may not agree with my reasoning, but that's how it seemed to me at the time.

nikhilsamuel89 · Answer

That the application of new technology can increase the productivity of existing coal mines is demonstrated by the case of Tribnia’s coal industry. Coal output per miner in Tribnia is double what it was five years ago, even though no new mines have opened.
 \frac{C o 5yrs ago}{N5 yrs ago}  =  2*\frac{C o now}{Nnow} 
Draw a Conclusion: For such questions, we should not assume anything other than what is given in the premises.
A. If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia’s total coal production has doubled in that period of time. Only option that can be logically inferred without any assumptions.
B. Any individual Tribnian coal mine that achieved an increase in overall output in the past five years has also experienced an increase in output per miner.   Out of Scope . Nothing about individual coal mines is mentioned. 
C. If any new coal mines had opened in Tribnia in the past five years, then the increase in output per miner would have been even greater than it actually was.  Further assumption required .Out  
D. If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine’s overall output has declined or remained constant.   It may be possible that the number of workers has declined.  Out. 
E. In Tribnia the cost of producing a given quantity of coal has declined over the past five years.   Out of Scope . Nothing about price mentioned.

egmat · Answer

I got a PM to respond to this one, especially to clarify why choice B is not the correct answer.

There are two things to keep in mind in this question:

1. You are looking of information that must be true based on the information in the argument. 
2. The information in the argument talks about averages - Average increase of coal output per miner across the country and not for any specfic mine. Note that the argument does not state that the output per miner should have increased by the same amount in every mine in the country. It does not even imply that the output of every mine should have increases. Its only talking about averages or that increases in output and productivity per miner coincide for every mine.

Choice B : Choice B is an example of the  specific instance  that is described in #2 above that cannot be inferred from the data in the argument. The argument does not state that every mine that has experienced increased output has also experienced increased productivity.

Let me know if you need more explanation.

-Rajat

monsoon1 · Answer

Is the assumption in the above argument is that " new technology has helped the workers to increase the productivity over the year"and based on that answer choice A (which mentions additionally that number of workers remained constant) is correct?

Please explain.

egmat · Answer

Dear Monsoon,

This is a conclusion question. Can you tell me why are you looking for assumptions in this questions. Essentially, in conclusion/Must Be true question types, we are only concerned with information that is mentioned in the argument. Assumptions, by definition, are not mentioned in the argument.

Here is the reason why choice A is correct:

The argument states that coal output per miner has doubled. Hence, if the coal output per miner was 100 tonnes/yr 5 yrs back, it is 200 tonnes per year now. The argument also states that no new mines have opened.

Total coal production = (Number of Miners) X (Production per Miner)

Hence, if Number of Miners is unchanged, and the production per Miner has doubled (as per the argument), the total production will double.

Let me know if this is not clear.

-Rajat

rango · Answer

Good One;
The passage states that;
Tech leds to increased production leads to 2x coal/ miner than five years ago; no new mines opened.
A. If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia's total coal production has doubled in that period of time.
I guess this exactly concludes the statement that no. of miners are constant hence the technology is effective to increase the proaction / miner to double in five years.

B. Any individual Tribnian coal mine that achieved an increase in overall ouput in the past five years has also experienced an increase in output per miner.- Reverse logic trap; if A is increased and B is unit of A ; so B increased.

C. If any new coal mines had opened in Tribnia in the past five years, then the increase in output per miner would have been even greater than it actually was. Irrelevant comparison

D. If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine's overall output has declined or remained constant. Reverse logic trap; if A is not increased and A has no. of B then B is not increased

E. In Tribnia the cost of producing a given quantity of coal has declined over the past five years. Distraction The price is not discussed in the passage. Sort of out of scope option.

:banana

Explanations with answers please. OA to follow.[/quote]

Explanations with answers please. OA to follow.

mallya12 · Answer

I understand option A but how do we eliminate answer choice B

Rajeet123 · Answer

I was confused between A and B, and chose B. Can you explain why not B?

GMATNinja · Answer

From the passage, we know that "coal output per miner in Tribnia is double what it was five years ago." Let's apply this information to the answer choices in question:

Notice that the evidence in the passage gives an increase in the  overall  coal output per miner in Tribnia. If we know that the overall rate doubled, can we conclude that any  individual  mine that achieved in increase in output also increased its output per miner?

In short -- no, we cannot conclude that. It is possible that some mines hired a bunch of additional miners, and even if their output increased, their output  per miner  stayed the same (or even decreased). The overall rate of coal output per miner must average out to be double the overall rate of five years ago, but we cannot conclude that any individual mine increased its rate of coal output per miner. (B) is out.

Now look at (A):
 
Again, the key piece of information in the passage to apply here is that "coal output per miner in Tribnia is double what it was five years ago." If each miner is, on average, producing double the amount of coal now that each miner produced five years ago, and if the number of miners has remained the same, then the total coal production must have doubled as well.

Think of it this way: Five years ago, 100 miners produced 100 tons of coal per day (is this a reasonable amount of coal? I have no idea). Now, there are still 100 miners, but their productivity has doubled. What is their total output? It is, of course, double what it was before -- so, 200 tons. Because the rate has doubled and the amount of workers has remained constant, the overall output must have doubled as well. (A) is our answer.

I hope that helps!

KarishmaB · Answer

In Tribnia, coal output per miner in Tribnia is double what it was five years ago, even though no new mines have opened.

Note that we are talking about coal output/miner = Total coal output / No of miners

This quantity will depend on how total coal output has changed and how no. of miners has changed. If it has doubled, it is possible that coal output has doubled while no of miners is same. It is possible that number of miners has become half while coal output is same. It is possible that output has become 4 times while no of miners has doubled and so on...

(A) If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia's total coal production has doubled in that period of time.

Correct. If number of miners has remained the same, then the total output must have doubled.

(B) Any individual Tribnian coal mine that achieved an increase in overall ouput in the past five years has also experienced an increase in output per miner.

Not true. If the output increased but number of miners increased too, output per miner may not have increased.

(C) If any new coal mines had opened in Tribnia in the past five years, then the increase in output per miner would have been even greater than it actually was.

No. It depends on the number of miners, output of rest of the mines etc.

(D) If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine's overall output has declined or remained constant.

Not true. A mine may have increased its output but increased its number of miners too. In that case, its output per miner may not have increased though its output would have increased.

(E) In Tribnia the cost of producing a given quantity of coal has declined over the past five years.

Nothing known about cost of producing coal.

Answer (A)

energetics · Answer

What we know ==> #coal per miner is now double compared to 5 years ago, 0 new mines

(A) If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia's total coal production has doubled in that period of time.  
 GMATNinja   VeritasKarishma  
 When I read this AC, I thought total amount of coal would not necessarily double over the 5 year period if there was a downturn in one of the years -- that 2*ratio now at some point in the past was not true. Did I just confuse ratio and numerical value? Presumably the statement would need something like "now" or "this year" and "total amount of coal" to make it mean what I thought?

(B) Any individual Tribnian coal mine that achieved an increase in overall output in the past five years has also experienced an increase in output per miner. 
First of all we can't talk about individual mines, out of scope. Also, it's possible they hired more miners so output could stay the same or even decline.

(C) If any new coal mines had opened in Tribnia in the past five years, then the increase in output per miner would have been even greater than it actually was.  
Could be true, but not must be true because the new mine could just have the same rate of output per worker and therefore output would stay the same.

(D) If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine's overall output has declined or remained constant. 
Could be true only and out of scope as before. Can't talk about individual mines and increase in miners could increase overall output but have a reduced coal output per miner.

(E) In Tribnia the cost of producing a given quantity of coal has declined over the past five years. 
Obviously out of scope since price is not mentioned.

KarishmaB · Answer

Coal per miner has doubled in the last 5 years. This means:

(Total Coal in 2019/ No of miners in 2019) = 2 * (Total Coal in 2014/ No of miners in 2014)

It is not necessary that it has increased every year. From 5 yrs ago to today, this is the status.

Option (A) tells us that No of miners has stayed constant. So 
No of miners in 2019 = No of miners in 2014

This means Total Coal in 2019 = 2 * Total Coal in 2014

Hence option (A) holds.

KarishmaB · Answer

In Tribnia, no new mines have opened.
In 5 yrs, Coal output per miner in Tribnia has doubled.
New technology can increase the productivity of existing coal mines is demonstrated by the case of Tribnia's coal industry

We need an option that must hold true as per this argument.

Coal output/miner has doubled. What does this mean? How do we calculate coal output per miner?

Coal output per miner = Total Coal Output of Tribnia/Total number of miners in Trbinia

If this has doubled, either Total coal output doubled, or total number of miners halved or some combination of both. 
Note that output of one mine or number of miners in one mine is irrelevant. We are talking about total output of all mines together in Tribnia and of all miners together in Tribnia.

(A) If the number of miners working in Tribnian coal mines has remained constant in the past five years, Tribnia's total coal production has doubled in that period of time.

Correct. If number of miners is constant, then total coal production must have doubled.

(B) Any individual Tribnian coal mine that achieved an increase in overall ouput in the past five years has also experienced an increase in output per miner.

Individual coal mines are irrelevant. Anything could have happened in one mine. It could have increased its output as well as increased its number of miners such that that output per miner might have stayed same or even reduced.

(C) If any new coal mines had opened in Tribnia in the past five years, then the increase in output per miner would have been even greater than it actually was.

We don't know. If a new mine had opened, total output may have increased but number of miners may have increased much more leading to decrease in output per miner.

(D) If any individual Tribnian coal mine has not increased its output per miner in the past five years, then that mine's overall output has declined or remained constant.

As we said, anything could have happened in an individual mine. If a mine has not increased its output per miner, it is possible that its overall output has increased but number of miners has increased even more. Not correct.

(E) In Tribnia the cost of producing a given quantity of coal has declined over the past five years.

Irrelevant.

Answer (A)

That the application of new technology can increase the productivity o

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