Traveler: Southern Airways has a far worse safety record than Air Dace

Question

Traveler: Southern Airways has a far worse safety record than Air Dacentaria over the past few years, in terms of both the frequency of accidents and the severity of accidents. Therefore, although Air Dacentaria is slightly more expensive, I will choose it over Southern Airways for my flight from Pederton to Dacenta, since it is worth paying extra to have a safer flight.

Which of the following, if true, casts the most serious doubt on the traveler's argument?

A. Air Dacentaria's flight from Pederton to Dacenta is nonstop, whereas Southern Airways' flight touches down in Gorinda on the way.

B. Most Southern Airways flights, but not its flight from Pederton to Dacenta, use Sarmouth airport, which because of its mountainous location is one of the world's most dangerous.

C. For its flights from Pederton to Dacenta, Southern Airways uses a different model of airplane, with a smaller capacity, than the model Air Dacentaria uses for its flights on the same route.

D. Only in the last few years has the cost of flying from Pederton to Dacenta been more expensive on Air Dacentaria than on Southern Airways.

E. Although the frequency of accidents is greater on Southern Airways, on both airlines the proportion of flights that have accidents is very small.

Zarrolou · Accepted Answer

The argument says that Southern Airways has a far worse safety record that Air Dacentaria
Therefore, although Air Dacentaria is slightly more expensive, I will choose it over Southern Airways for   my flight from Pederton to Dacenta.

Since the overall safety is worse for the SA => also on a specific flight the safety is worse.  This is the argument of the text.

The correct answer will destroy this connection somehow: will show that the data is not reliable or that there are distortions, and so on...

B and E...

B. Most Southern Airways flights, ut not its flight from Pederton to Dacenta, use Sarmouth airport, which because of its mountainous location is one of the world's most dangerous. 
B says that the overall rate of accidents is overestimated because SA uses a particular airport that is dangerous. So we can infer that, if SA stops using that airport, its safety level would be higher than that of the other company; and because the person will not flight in that airport, the argument is weakened.(This answer shows that the overall data is not a reliable indicator because suffers from the low safety of a single airport).

E. Although the frequency of accidents is greater on Southern Airways, on both airlines the proportion of flights that have accidents is very small. 
E does not affect the conclusion.  "on both airlines the proportion of flights that have accidents is very small"  => when comparing different companies the most important stats are the percentages (not the overall number), and E says that under this point of view there is no difference between the two companies.

cdm2006 · Answer

I go for B (if I remember correctly this is a question from GMATPrep): reason: The travel prefers safety, and argues that Southern Airways has a worse safety record than Air Dacentaria. Now you have to find a reason that explains why safety for THIS particular flight shouldn't be worse. B gives you an explanation why Southern Airways usually is less safe but not in this flight

mrmikec · Answer

I picked E originally but this is why i think E is wrong...

although the proportions of accidents is small, SA may still have a greater accident rate than AD. thus his conclusion still holds, AD is safer.

B weakens it by giving an alternative explanation to why it SA is unsafe. Weakens the premise that SA is unsafe overall; stats are skewed b/c of that one airport.

SherLocked2018 · Answer

B for me too. Reasons given : 
A. Air Dacentaria's flight from Pederton to Dacenta is nonstop, whereas Southern Airways' flight touches down in Gorinda on the way.    
B. Most Southern Airways flights, ut not its flight from Pederton to Dacenta, use Sarmouth airport, which because of its mountainous location is one of the world's most dangerous.    
C. For its flights from Pederton to Dacenta, Southern Airways uses a different model of airplane, with a smaller capacity, that the model Air Dacentaria uses for its flights on the same route.    
D. Only in the last few years has the cost of flying from Pederton to Dacenta been more expensive on Air Dacentaria than on Southern Airways.    
E. Although the frequency of accidents is greater on Southern Airways, on both airlines the proportion of flights that have accidents is very small.    
Thus B.

ravikrishna1979 · Answer

B says due to airport location, more accidents occurs. So what? accidents still occur whether it is due to clouds or pilots or whether or other reason.

E says the proportion is same, means the % of accidents are same. What does that mean? Higher no.of flights do not encounter accidents which can assure that it is safer.

StoicBread · Answer

No, B is saying that the majority Southern Airway's accidents happen at a different airport than the one the person is flying out of. Meaning the flight that he/she is taking is actually safe, so there is no reason to spend the extra money to fly on the aggregately safer airline.

For E, proportions of safe flights to crashes are inherently low for airlines but even small differences in crash rates can have huge impacts on the number of crashes.

GDT · Answer

Why is E not the answer

It also weakens the support for conclusion by saying the rates of accident for both are same

AndrewN · Answer

Watch those assumptions,  GDT . Look at choice (E) again:

Very small  is not synonymous with  the same , nor can you qualify exactly what  very small  means, in terms of numbers. 1 percent? 5 percent? Can we say that each airline has the same proportion of flights that have accidents? No. You should also know from studying Quant that a proportion and a number of something are not necessarily the same. The conclusion could very well hold true, given this new information. In choice (B), if only Southern Airways uses this most dangerous airport,  but not on the very flight the traveler is taking , from Pederton to Dacenta, then there seems to be no compelling reason  within the information provided  for the person to assume that flying Air Dacentaria will be any safer. That is what we are after here, the best, most reasonable answer of the five given. Choice (E) simply requires too much speculation to work.

I hope that clarifies your doubts. If you have further questions, I would be happy to help out.

- Andrew

kashking · Answer

@KarishmaB
Maam, one fundamental doubt - in these kind of questions, what should we weaken?
Should we say that in general the Southern Airways is better than the other airlines or in this specific route, the airline is better?

What exactly should be the weaken statement?

MartyMurray · Answer

What we need to weaken is the support for the author's conclusion.

The support the author provides for that conclusion is this general statement:

Southern Airways has a far worse safety record than Air Dacentaria over the past few years, in terms of both the frequency of accidents and the severity of accidents.

At the same time, the conclusion is not a general statement. It's the following specific statement:

I will choose it (Air Dacentaria) over Southern Airways for my flight from Pederton to Dacenta.

So, we need to weaken the support for the choice of Air Dacentaria over Southern Airways for the flight from Pederton to Dacenta.

KarishmaB · Answer

Premises: Southern Airways has a far worse safety record than Air Dacentaria over the past few years, in terms of both the frequency of accidents and the severity of accidents. Air Dacentaria is slightly more expensive. It is worth paying extra to have a safer flight. Conclusion: I will choose Air Dacentaria over Southern Airways for my flight from Pederton to Dacenta.  The premises talk about Southern Airways’ worse safety record and the conclusion concludes about a particular flight (from Pederton to Dacenta). We need to weaken the conclusion. A. Air Dacentaria's flight from Pederton to Dacenta is nonstop, whereas Southern Airways' flight touches down in Gorinda on the way. Irrelevant to our argument. We don’t know how non-stop vs one stop impacts the decision of the traveller.   B. Most Southern Airways flights, but not its flight from Pederton to Dacenta, use Sarmouth airport, which because of its mountainous location is one of the world's most dangerous. It tells us that the bad statistics of Southern Airways is because it extensively uses the Sarmouth airport - a very dangerous airport. But for its flight from Pederton to Dacenta, it doesn’t use that airport. Hence it casts doubt on the traveller’s decision of not using Southern Airways for his flight due to its bad safety record. The safety record of the airline would not be the same as the safety record for the flight which he wants to take.   Correct.   C. For its flights from Pederton to Dacenta, Southern Airways uses a different model of airplane, with a smaller capacity, than the model Air Dacentaria uses for its flights on the same route.   Irrelevant to our argument. We don’t know how a smaller vs bigger plane impacts the decision of the traveller. D. Only in the last few years has the cost of flying from Pederton to Dacenta been more expensive on Air Dacentaria than on Southern Airways.  Irrelevant to our argument. We know that Air Dacentaria has a more expensive flight. Despite that, the traveller wants to take it. When did it become more expensive, doesn’t matter.  E. Although the frequency of accidents is greater on Southern Airways, on both airlines the proportion of flights that have accidents is very small. Irrelevant to our argument. We are talking about relative figures. Relative to Air Dacentaria, Southern Airways has worse figures. That is why the traveller prefers one over the other. Whether in absolute terms the figures are bad or not is irrelevant. Answer (B) Discuss on Weaken Questions: https://youtu.be/EhZ8FKkfy0k

agrasan · Answer

Hi experts  MartyMurray   KarishmaB   GMATNinja 
Is option E wrong because it is not talking about the specific route "flight from Pederton to Dacenta" and rather talks about all flights? My thinking is we shouldn't care about all flights. Please let me know.

MartyMurray · Answer

That's not really a good reason to eliminate (E).

The support for the conclusion is that Southern Airways has a worse flight record overall. So, the support involves all flights of the two airlines. Thus, information about all flights could weaken the case for the conclusion.

In fact, notice that the information provided by the correct answer in a way involves all flights as well.

The best reason to eliminate (E) is that, regardless of what (E) says, Air Dacentaria still has a better safety record. So, even if (E) is true, the argument still works.

GMATNinja · Answer

Marty (hello, Marty!) has you covered nicely, but I'll toss in an extra example in case it helps.

As Marty mentioned, (E) just tells us that the accident rate is very small for BOTH airlines. That does not, however, change the fact that Southern Airways has a  far worse  safety record than Air Dacentaria over the past few years.

For example, maybe Air Dacentaria has one accident for every million flights while Southern Airways has 10 accidents for every million flights. Both accident rates are very small, but Southern Airways' accident rate is 10 times worse than Dacentaria's.

I hope that helps a bit!

rushimehta · Answer

Although, I understand why B will be the answer here...

Can someone please help me understand the difference between "frequency of accidents" and "the proportion of flights that have accidents"...?

Is 
"frequency of accidents" --> lets say, number of accidents/year...
and "the proportion of flights that have accidents" --> flights having accidents/total number of flights (this is clear from the example  GMATNinja  provided)

So based on above definitions, it could be that - Even if Southern Airways has a higher  frequency  (more total accidents), the  proportion  could still be small if it operates far more flights.

Also, just in case, tweaking option E a bit (based on the above definitions)... if E says that

Although the frequency of accidents is greater on Southern Airways, the proportion of flights that have accidents on southern airways is smaller than that of Air Deccantaria.

The above tweaked option, would still won't be as strong weakner as B weakener is - this option, though weakens the statistics given, it still doesn't speak about the specific flight route the traveler is taking...

Is my understanding correct. ??? 
(Also, I hope that I am able to communicate my thoughts clearly)

Thanks in advance!!!

GMATNinja   MartyMurray   KarishmaB

KarishmaB · Answer

Yes, frequency of accidents would be say SA has 3 accidents/year while AD has 2 accidents/year. So frequency for SA is higher. 
But SA has say 10000 flights every year while AD has 100 flights only - So proportion of flights that have accidents for SA is far lower (only 3/10000) while it is much higher for AD (2/100) and hence SA is safer comparatively (probability of accident on taking an SA flight is lower)

If you tweak option (E) as suggested, it becomes a weakener too. GMAT won't give you 2 such options.

Traveler: Southern Airways has a far worse safety record than Air Dace

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Traveler: Southern Airways has a far worse safety record than Air Dace

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