The price of a full-fare coach ticket from Toronto to Dallas on Breeze

Bunuel, yashikaagarwal nightblade354 could either of you as and when possible, please illuminate me why is B correct and D wrong ?

Thank you.

Hi, this question is a sufficient assumption question, not a necessary assumption question. The GMAT deals with necessary assumption exclusively (where negation works), while the LSAT uses a second set called sufficient assumption, where negation does not work because the statement is not needed to make the argument work.

You can ignore this. However, if you want to practice it, try using the answer choices as premises to help build a bridge from the premises to the conclusion. Whichever answer choice helps build that bridge will be our answer.

I dont agree with the answer ..


(B) A Toronto-to-Dallas discount coach ticket on Breezeway Airlines costs about the same in constant dollars as they did a year ago.

Why this is necessary to be assumed .. If the price discount coach ticket doesn't remains the same( it can't be less also), in that case also avg cost will come down .. Then how the assumption of costs to remain same is valid ??

I initially chose D but now understand why B is the correct answer.

D actually weakens the conclusion that on average, people pay less today in constant dollars for a Breezeway Toronto-to-Dallas coach ticket than they did a year ago because let's assume that a year ago there were 10 passengers and the cost of a full-price ticket was $4 and the cost of a discount ticket was $2. This means that a year ago, revenue (i.e. how much people pay for a coach ticket) for Breezeway was (5*2) + (5*4) = $30 accordingly to the prompt which states that a year ago half were discount tickets and half were full-fare tickets

If D was correct that The average number of coach passengers per flight that Breezeway Airlines carries from Toronto to Dallas today is higher than the average number per flight a year ago then we can also assume that the no of passengers is now 20 and if from the question, today 90 percent of the Toronto-to-Dallas coach tickets that Breezeway sells are discount tickets and only 10 percent are full-fare tickets then it means that the revenue for Breezeway is now (18*2) + (2*4) = 44 which is actually higher and weakens the conclusion.

B is the more correct answer because it fills an assumption gap.

The gap that Breezeway didn't reduce the discount it gives on its ticket and thus increase the price of discount tickets i.e. using my previous scenarios, Breeway didn't increase the discount ticket price from say 2 to 3 (which would still be a discount but a higher price). Because if Breezeway increased the discount ticket price then the conclusion that Breezeway's total revenue has reduced could be false. The prompt also don't include any premise that speaks about the price of the discount tickets. It only says The price of a full-fare coach ticket from Toronto to Dallas on Breezeway Airlines is the same today as it was a year ago thus I think B appropriately fills this gap and allows the conclusion to be properly drawn.

What do you think?

I could POE all except B and C.

For B my reasoning is as follows:-

Today 90% pay discounted rates. Last year only 50% pay discounted rates.
So today people pay less.

Gap in argument ---> If after discount the last year guys pay lesser than today's guys then argument weakens because we don't know the discount %. We only know the initial prices for both people are same (taking into account the inflation as well).

Therefore, what about prices AFTER the discount?
Say initially both cost $100. We don't know the discount rate. So after discount who pays more or less?

B fulfills that gap.

(B) A Toronto-to-Dallas discount coach ticket on Breezeway Airlines costs about the same in constant dollars as they did a year ago.
This says that after discount both pay same. Therefore, if this is true, and we also consider the inflation, clearly todays guys should've paid little more (but they aren't). Thus, today's guys have it cheap. B is a necessary assumption.

Also for C I had no clue. But I could see why D was THE ONE.

Regards,
Saakhi

Understanding the argument - 
­The price of a full-fare coach ticket from Toronto to Dallas on Breezeway Airlines is the same today as it was a year ago, if inflation is taken into account by calculating prices in constant dollars. - Background info. Example:
The price of the tickets last year was $200, and say the inflation is 5%. If we were to take inflation into account, this year's price would be $210. But as the price remains the same, this year will still be $200. 

However, today, 90 percent of the Toronto-to-Dallas coach tickets that Breezeway sells are discount tickets, and only 10 percent are full-fare tickets, whereas a year ago, half were discount tickets and half were full-fare tickets. - "However" introduces the contrast. Example:
Last year - Full price = $200
50% at a discounted price, say for $100
50% at Full price 
Average = 50% * 100 + 50% *200 = $150

This year = Full price = $200
90% at a discounted price say for $100
10% at Full price 
Average = 90% * 100 + 10% *200 = $110

Therefore, on average, people pay less today in constant dollars for a Breezeway Toronto-to-Dallas coach ticket than they did a year ago. - Conclusion 

Which one of the following, if assumed, would allow the conclusion above to be properly drawn?

Option Elimination - We need to find an assumption, missing premise, or assumption. 

(A) A Toronto-to-Dallas full-fare coach ticket on Breezeway Airlines provides ticket-holders with a lower level of service today than such a ticket provided a year ago. - "level of service" is out of scope. 

(B) A Toronto-to-Dallas discount coach ticket on Breezeway Airlines costs about the same in constant dollars as they did a year ago. - Yes. The discounted prices of $100 are the same as last year and this year. Say if this is not true. If the discount price this year is $190, then the average price will be = 90% * 190 + 10% * 200 = $198. Then the conclusion breaks as the price from last year has increased from $150 to $198. 

(C) All full-fare coach tickets on Breezeway Airlines cost the same in constant dollars as they did a year ago. - Restating the premise. Wrong. 

(D) The average number of coach passengers per flight that Breezeway Airlines carries from Toronto to Dallas today is higher than the average number per flight a year ago. - " The average number of coach passengers per flight" is out of scope from an "on average, people pay less today" perspective. 

(E) The criteria that Breezeway Airlines uses for permitting passengers to buy discount coach tickets on the Toronto-to-Dallas route are different today than they were a year ago. - Yes, it may be, but that doesn't help with the scope, which is to find the missing premise for the conclusion: "On average, people pay less today in constant dollars for a Breezeway Toronto-to-Dallas coach ticket than they did a year ago."