GMAT 逻辑分析题 (2)

sdcar2010

The price of a full-fare flight ticket from Beijing to Shanghai on Air China is the same today as it was a year ago, if inflation is taken into account by calculating prices in constant RMB. However, today 80% of the Beijing-to-Shanghai flight tickets that Air China sells are discount flight tickets and only 20% are full-fare flight tickets, whereas a year ago half were discount flight tickets and half were full-fare flight tickets. Therefore on average, people pay less today in constant dollars for an Air China Beijing-Shanghai flight ticket than they did a year ago.

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

A) A Beijing-to-Shanghai full fare flight ticket on Air China provides ticket-holders with a lower level of service today than such a ticket provided a year ago.

B) The average number of coach passengers per flight that Air China carries from Beijing to Shanghai today is higher than the average number per flight a year ago.

C) All full fare flight tickets on Air China cost the same in constant dollar RMB as they did a year ago.

D) A Beijing-to-Shanghai discount flight ticket on Air China costs about the same amount in constant dollars today as it did a year ago.

E) The criteria that Air China uses for permitting passengers to buy discount flight tickets on the Beijing-to-Shanghai route are different today than they were a year ago

kevin0214

D吧。ABE显然都不对，C和D我看了好久以为没区别，最后突然想如果C能够用那么短的文字表达同样的意思，D还要说那么多废话干吗，这才发现有个ALL，C的范围太大了，是充分条件，但不是必要条件，所以不是ASSUMPTION。
sdcar2010你发的问题很有意思，在哪里找的？还有我很佩服你可以用纯英文那么简洁清晰地讨论逻辑题。

sdcar2010

Kevin, well done!

(C) actually is simply repeating what the stimulus says in the first sentence.

(D), as you just said, is a necessary assumption.  If today's discount is only 1% off the full fare while the discount last year was 99% off the full fare, the conclusion would be totally wrong.

kevin0214

(D), as you just said, is a necessary assumption.  If today's discount is only 1% off the full fare while the discount last year was 99% off the full fare, the conclusion would be totally wrong.
我想的有点不同，选项里的意思应该是去年和今年的打折机票是一个价。而不是说今年的折扣和去年的折扣量是一样的。前提和结论之间的GAP应该是RMB和DOLLARS，第一句话已经说了用RMB衡量的价格一样，结论要美元，那应该是要求汇率稳定，至少美元买的机票价钱没变。不过你说的折扣量似乎也很重要。

sdcar2010

Oops, the dollar should be changed to RMB.  My bad.  Considering the existence of the typo, you DO have point to eliminate C according to the difference between RMB and dollar.

I will change the answer C right away.

suntree846

dear sdcar2010, as you said, one of the prompts for sufficient assumptions is: the author's conclusion would be properly drawn if which one of the following was true?  i believe this sentence is similar with the question above:Which one of the following, if assumed, would allow the conclusion above to be properly drawn?
so, why the correct answer we are looking for should be a necessary assumption but not a sufficient one? because the text has already given another necessary assumption:The price of a full-fare flight ticket from Beijing to Shanghai on Air China is the same today as it was a year ago, and the combination of (D) and this one is both sufficient and necessary for the conclusion?

sdcar2010

Good catch. D) in fact, is not a necessary assumption, but a sufficient one. A necessary condition would be: Last year'd discount price was not drastically lower than that of this year.

suntree846

thank you!

jiajiajudy

原来是C 的范围太大了，这里只要北京到上海， D的话我有个疑问，就是如何保证票子的原价是一样的？ 还是说题目的第一句已经提到全票价是一样的，所以可以不提？

A) A Beijing-to-Shanghai full fare flight ticket on Air China provides ticket-holders with a lower level of service today than such a ticket provided a year ago. -------------- not mentioned

B) The average number of coach passengers per flight that Air China carries from Beijing to Shanghai today is higher than the average number per flight a year ago. ---------------- irrelevant

C) All full fare flight tickets on Air China cost the same in constant dollar RMB as they did a year ago.
-------------- constant cost, correct， 我错了，范围太大
D) A Beijing-to-Shanghai discount flight ticket on Air China costs about the same amount in constant dollars today as it did a year ago. ----------------- don’t know the origin cost  这个是正确答案

E) The criteria that Air China uses for permitting passengers to buy discount flight tickets on the Beijing-to-Shanghai route are different today than they were a year ago -------------- irrelevant

summer5270

In the year following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent.  In contrast, in the year prior to the tax increase, sales had fallen one percent.  The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.

The argument above requires which of following assumptions?


A.During the year following the tax increase, the pretax price of a pack of cigarettes did not increase by as much as it had during the year prior to the tax increase.
B.The one percent fall in cigarette sales in the year prior to tax increase was due to a smaller tax increase.
C.The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase.
D.For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year.
E.As the after-tax price of a pack of cigarettes rises, the pretax price also rises.

D is correct, but i choose A. i don't know why Ais wrong. can you explan it thank you!!!
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The total market value of real estate in Altonville has steadily declined over the past four years.  This decline has meant that the overall figure on which the city's property tax is based ─ the assessed value of that real estate ─ has also declined.  Moreover, the percentage of assessed value that was paid as property taxes to the city did not change during this period.

The information above most strongly supports which of the following?
A.Money collected from property taxes provided most of Altonville's revenue during the past four years.
B.The percentage of Altonville's overall revenue that was collected from property taxes did not change over the past four years.
C.Altonville officials had proposed raising property tax rates during the past four years but never did so because of strong opposition from property owners.
D.The total amount of revenue that Altonville has collected from property taxes has declined over the past four years.
E.During the past four years, Altonville officials also did not increase tax rates on other sources of revenue such as retail sales or business profits.

D is correct, but i choose B. in the pasage"the percentage of assessed value that was paid as property taxes to the city did not change during this period." so the revenue which is collected from property taxes not change. where is wrong?