经典陈向东逻辑题请教

ejbchang

陈向东<<假设>>第30题:

Although the ratio of physicians to total population is about the same in the United states and Canada, the United States has 33 percent more surgeons per capita. Clearly, this is the reason people in the United States undergo 40 percent more operations per capita than do Canadians.

  The explanation given above rests on an assumption that

   A  patients in the United States do mont have a greater need for surgery than do patients in Canada.

  B  the population of the United States is not larger than that of Canada.

  C  United States patients sometimes travel to Canada for certain kinds of surgery.

  D  general practitioners in the United States do not as a rule examine a patient who is a candidate for surgery beore sending the patient to a surgeon

  E there are no unnecessary surgical operations performed in Canada.

The answer is A  , Why?

 

the other problem:

       page 55, 44.  A recent report determined that although only three percent of driers on Maryland highways equipped their vechicles with radar detectors , thirth-three percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not.

 The conclusion drawn above depends on which of the following assumptions?

A Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.

B  Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.

C  The number of vehicles that were tickedted for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.

D  Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.

E Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.

the answer is B

If don't use the method of layout , why the answer is B?  who can infer the above problems ?   happy national day.

    

ejbchang

ranning

1: 说A就是B发生的原因，所隐藏的假设是：排除其它的原因。可以当成加强来做

2. 文章说被ticketed的车子装了radar，而结论说drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not

中间缺少桥梁：被ticketed的车子的driver更容易exceed the speed limit regularly
    

crazecat123

1. it's A because if Americans have a greater need for surgery than Canadians do, then the extra per capita surgeons will be balanced out by the greater need, thus the conclusion that Americans undergo 40% more surgeries cannot be established.

2. Reverse the meaning of answer B: Drivers who are ticketed for exceeding the speed limit are more likely NOT to exceed the speed limit regularly than are drivers who are not
ticketed.
Does that still establish the conclusion?  The answer is no.
In other words, if the 33% of people caught have radar detectors with only 3% of total population who have installed them is clearly indication that most of these people caught are repeat offenders.

ejbchang

感谢支持!! 好人那!