PrepTest 107

[lcid:3524] Prep Test 107 LSAT — Logical Reasoning — S1 Logical reasoning

Question prompt

The price of a Remaining source text redacted.
Why the credited answer is right

Credited answer: B

The notes below walk through why it fits the stem and how to eliminate the rest.

Argument or Facts

Argument

Valid or Flawed

Flawed

Question Type

Strengthen with Sufficient Premise Questions

Stimulus Summary

A year ago - Full-fare tickets cost X; 50% of tickets sold were full-fare
Today - Full-fare tickets cost X (same); 10% of tickets sold are full-fare
Conclusion - The average ticket price paid today is less than a year ago

Answer Anticipation

This argument is all about the comparison between today and a year ago. We learn that the price of a full-fare ticket hasn’t changed, but Breezeway is selling a lower percentage of full-fare tickets (and a higher percentage of discounted tickets). From this, the argument concludes that the average price paid per ticket is lower today than a year ago.
So the conclusion is all about the average, which is important for two reasons. First, it tells us that the number of tickets doesn’t matter, since a change in totals has already been taken into account in figuring the average out. Second, it tells us what information would need to be established to let us know whether it’s valid.
To figure out the average ticket price, we need to know the total amount paid for tickets, and the total number of tickets sold. The percentages of tickets that were full-fare and discounted lets us actually tell the latter, just by knowing that more people bought the cheaper tickets this year. However, we’re missing information on the former - the amount paid! We know that the full-fare tickets didn’t change in price, but the stimulus is silent as to the price of the discounted tickets.
To use an extreme example to highlight this, say that last year’s discounted tickets were 99% off, and this year’s discounted tickets are 5% off. If that’s the case, even though 90% of the tickets were discounted, the cost of those tickets was much higher than last year’s, and so the average price paid last year might be lower.
Let’s find an answer establishing something about the relative cost of the discounted tickets from year to year - we’re looking for something that says it stayed about the same (minor fluctuations would probably be fine with the 40% shift).

Answer choices

  1. A
    A Toronto–to–Dallas full-fare coach Remaining source text redacted.
    Why choice A is not credited
    The level of service is out of scope of the cost - that has more to do with the valueof the tickets.
  2. B
    A Toronto–to–Dallas discount coach Remaining source text redacted.
    Why choice B matches the stem
    If the discount tickets cost about the same, and they make up a higher percentage of the total sales, then the average price must have gone down. This answer guarantees the truth of the conclusion, so it’s the correct answer.
  3. C
    All full–fare coach tickets Remaining source text redacted.
    Why choice C is not credited
    We already know this is true of the relevant tickets (Toronto-to-Dallas), so applying it to all Breezeway tickets doesn’t add anything to the argument.
  4. D
    The average number of Remaining source text redacted.
    Why choice D is not credited
    The number of passengers per flight would be relevant in an argument about the total amount raised by fares, or profit (since the number of flights to serve a given number of customers is directly related to costs), but it’s out of scope about the average cost of tickets.
  5. E
    The criteria that Breezeway Remaining source text redacted.
    Why choice E is not credited
    The criteria doesn’t change the cost or percentage of total ticket sales, so this answer doesn’t add anything relevant. Also, in stating that it’s “different,” we don’t learn if it’s more or less expansive, so this answer is really unspecific!

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