作者Depp (記得去看moby)
看板GMAT
標題Re: [問題] OG12-CR-78
時間Sat Apr 10 22:47:05 2010
※ 引述《halaphone (Still Ballin)》之銘言：
: A recent report determined that although only 3percent of drivers on Maryland
: highways equipped their vehicles with radar detectors, 33 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 exced the speed limit regularly thatn are drivers who do not.
3%equip radar,33%ticket equip radar
Equip radar==>more likely to exceed speed limit regulary
: 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.
超速的人容易一直超速
取非,超速的人不會比一般沒超速的人更容易超速
假設1000個開車的人
超速100人次
30個裝Radar, 那照理來講頂多超速的佔3% 30個人
不過超速33%的人裝Radar,有330人次,因此代表30個裝雷達的人重複的超速
填補缺口
結論 more likely to exceed speed limit regulary
: c. The number of vehicles that were ticketed for exceeding the speed the 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
more than once 次數不是重點
取非 只有一次
對結論沒有影響
: e. Drivers on Maryland highways exceeded the speed limit more often than did
: drivers on other state highways not covered in the report.
: Ans: B
: 這題我想了很久，還是不明白為什麼要選B
: 我的思路是以下
: 題目的結論是有裝detector的人比較容易regularly的超速
: 問作者是基於那個assumption這麼說
: a.說的是有裝detector的人比沒裝的人較不容易接到罰單
: -這個跟作者的結論相反所以不選
: b.接到罰單的人通常都是愛超速的人
: -跟題目有一些關聯，我保留
: c.跟題目說的也沒有什麼關係而且他把不同類的事件拿來比較，我也第一步就刪掉
: d.感覺跟題目有關聯，我也保留
: e.扯到別的state去了，直接刪
: 最後剩下B, D決選
: 我選了D
: 請問我應該要怎麼解這種問assumption的問題??
: 我看完答案後猜會選B的原因是因為B說會接到罰單的人通常都是常超速的人
: 因為他們常超速，所以才會裝detector所以結論是裝detector的人都是愛超速的人
: 但這是我在看完答案後才知道要這樣去解釋，如果不看答案我就會選錯
: 不知道有沒有戰友可以提供更好的思路?
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推 pentimento:這題原文以「被開罰單中有裝測速器的比例」經比較後 04/11 07:54
→ pentimento:得出「有裝測速器比沒裝測速器」的容易超速。因此重點 04/11 07:54
→ pentimento:在於「被開罰單的」能夠代表「所有開車的」，因此是 04/11 07:55
→ pentimento:歸納類別的錯誤。因為有人超速卻不一定被開單，因此 04/11 07:56
→ pentimento:要補充的是「被開單中有測速器者的比例」能夠代表「所 04/11 07:57
→ pentimento:有超速者（包括沒被開單）中有裝測速器的比例」。 04/11 07:57
→ pentimento:而答案B說的卻是「被開單的比沒被開單的，容易超速」 04/11 07:58
→ pentimento:這與題目中，有裝測速器者的比例根本沒關係，無法用來 04/11 07:59
→ pentimento:當假設。將B取非，也無法推翻原文，所以原B也無法當 04/11 07:59
→ pentimento:假設。最後結論是，這題答案有問題。很久以前有討論過 04/11 08:00