71. Tipping, according to the studies of psychologists, ____.

1. is simply about service
2. depends on the waiter's service
3. can be affected by waiter's words
4. has nothing to do with the flavor of the food

72. Rick van Baaren and his colleagues surveyed that ____.

1. a group of 59 wait staff receives higher tips in American-styled restaurants
2. waiters not repeating the customers take their tips home
3. waiters imitating the customers earn as much as the other half
4. waiters imitating the customers earn twice as much as the other half

73. Tip percentages ____.

1. have no much difference among waiters, cab drivers and hair stylists v
2. may be limited by customer's generosity
3. increase as customers' bills go up
4. are almost the same for a bill topping 100 and a bill for 200

74. Green explains that ____.

1. a tip is related to success in life
2. people give a high tip in order to show up
3. sometimes a tip is for being there
4. portion makes up a large part of bills

75. According to the author, which of the following is least related with tipping?

1. Customer's mood
2. Waiter's service
3. Waiter's mimicry
4. Bill's amount

(Reference keys.)