Critical Reasoning

In a study conducted in Canada, servers in various restaurants wrote "Thank you" on randomly selected bills before presenting the bills to their customers. Tips on these bills were an average of three percentage points higher than tips on bills without the message. Therefore, if servers in Canada regularly wrote "Thank you" on restaurant bills, their average income from tips would be significantly higher than It otherwise would have been.

Which of the following is an assumption on which the argument relies?

(A)The "Thank you" message would have the same impact on regular patrons of a restaurant as they would on occasional patrons of the same restaurant.
(B)Regularly seeing "Thank you" written on their bills would not lead restaurant patrons to revert to their earlier tipping habits.
(C)The written "Thank you" reminds restaurant patrons that tips constitute a significant part of the income of many food servers.
(D)The rate at which people tip food servers in Canada does not vary with how expensive a restaurant is.
(E)Virtually all patrons of the Canadian restaurants in the study who were given a bill with "Thank you" written on it left a larger tip than they otherwise would have.

OA: B

Well, the answer is B.

The argument provides data indicating that writing Thank You on a few randomly selected bills resulted in higher tips. The conclusion, however, contains the word "regularly."

The argument assumes that once the novelty factor wears off, the practice will continue to result in higher tips.

A good method for finding assumptions is to look for new, surprising words in the conclusion that are not mentioned in the premises of the argument.