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?

1. 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.
2. Regularly seeing “Thank you” written on their bills would not lead restaurant patrons to revert to their earlier tipping habits.
3. The written “Thank you” reminds restaurant patrons that tips constitute a significant part of the income of many food servers.
4. The rate at which people tip food servers in Pennsylvania does not vary with how expensive a restaurant is.
5. 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.

Answer:

选B！

assumption题目，首先找否定词not，然后去掉not，看能不能weaken，如果weaken就是答案。这是狒狒逻辑宝典中的重要定理。

所以B选项去掉not，就是说，客人如果经常看到thank you的标记，就会回到以前的付小费的方式，那么自然不会多给那个3％，削弱结论。

A选项取非，就是说，thank you标记对于常客和临时的客人，影响不一样，那么到底多付小费还是少付小费，不知道。

right。应该是B。

狒狒关于assumption的定理应用范围广么？

狒狒说90％的assumption都是not+weaken的题目，我发现的确应用很普遍的。当然最爽的是5个选项里面只有一个带有not或者none之类的词汇，那么肯定选那个选项，比较麻烦的是有两三个都带有否定词汇，那就只能一个个看，none也经常是正确的选项的。