Question Regarding Chapter 3 Drill It Question

[Camiller]

Hi,

I have a question regarding drill it question #9 (PT29, S1, Q20) on page 123. I did get this question right, but I have a question regarding the explanation provided for one of the wrong answer choices. In the last paragraph of explanation for this question (pg. 137), it is stated that: "Answer (C) has two problems with it first of all, since we already know that the regular tickets cost the same amount, this is a premise booster. If you read with a close eye, you might have noticed that answer (C) is about all full-fare coach tickets. This argument is about only the Toronto-to-Dallas route."

I fully understand that (C) is incorrect as a premise booster. However, as this question is asking for a sufficient assumption, what is the problem with the answer choice using "all" (being about a more general group of tickets than just Toronto-to-Dallas tickets)?

A sufficient assumption can provide more support than what is required (go beyond the scope of the argument).

[ohthatpatrick]

True that!

You're right. The book's wrong. The explanation should read, "The answer has ONE problem with it: we don't care whether OTHER full fare tickets are the same. We only care whether the Toronto to Dallas DISCOUNT fare is the same."

Thanks for catching that so we can fix it for future editions.