[問題] GWD17-Q30

[elsachang]

GWD17-Q30:
In a study conducted in Pennsylvania, 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 Pennsylvania 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” messages 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 Pennsylvania does not vary with how expensive a restaurant is.
E.Virtually all patrons of the Pennsylvania restaurants in the study who were given a bill with “Thank you” written on it left a larger tip than they otherwise would have.

我選A, 答案給B

選A的原因是, "Thank you" 紙條的作用必須對常來的客人一樣有持續的效果 (因為可能一次兩次之後他們習慣了,就不會再給小費了), 而偶爾來的客人因為是偶爾來, 所以看到紙條多會給小費

答案B說"經常看到Thank you 紙條,不會讓客人回復/回想以前的給小費習慣", 我疑惑的是, 我們怎麼知到客人以前給小費的習慣是什麼樣子? (對這題目應該一點關係都沒有吧....) 以前給小費的習慣在這裡當auumption的意義是啥阿?