[求助]GWD31套数学讨论：第一套

xin861123

各位战友，小弟在网上找了许久也没有看到GWD31套数学的讨论，很多都是讨论VERBAL的，但数学里很多题目知道答案却还是不知道怎么做，（过程！！）想在此向给位高手求救！！

Q2:

A certain roller coaster has 3 cars, and a passenger is equally likely to ride in any 1 of the 3 cars each time that passenger rides the roller coaster.  If a certain passenger is to ride the roller coaster 3 times, what is the probability that the passenger will ride in each of the 3 cars?

A.      0

B.      1/9

C.      2/9

D.      1/3

E.       1

Answer:

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Q10:

A set of numbers has the property that for any number t in the set, t + 2 is in the set.  If –1 is in the set, which of the following must also be in the set?

I.                 -3

II.               1

III.             5

A.    I only
      

B.    II only

C.    I and II only
      

D.   II and III only
      

E.    I, II, and III
      

Answer:

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Q14:

If 10⁵⁰ – 74 is written as an integer in base 10 notation, what is the sum of the digits in that integer?

A.     424

B.     433

C.     440

D.    449

E.     467

Answer:

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Q26:

Running at their respective constant rates, machine X takes 2 days longer to produce w widgets than machine Y.  At these rates, if the two machines together produce 5/4 w widgets in 3 days, how many days would it take machine X alone to produce 2w widgets?

A.     4

B.     6

C.     8

D.    10

E.     12

Answer:

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Q31:

A positive integer n is said to be “prime-saturated” if the product of all the different positive prime factors of n is less than the square root of n.  What is the greatest two-digit prime-saturated integer?

A.     99

B.     98

C.     97

D.    96

E.     95

Answer:

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答案：C D C E D

[此贴子已经被作者于2008-3-27 11:49:30编辑过]

maryibsb

你好,

    以下提供我的做法給您參考一下:

Q2: 坐3次rollercoaster每一次都有可能坐到三個車廂的其中一個,坐三次共有3*3*3種可能,而如果每一次都要坐到不同車廂,第一次有三種可能,第二次便只有2種可能,到第三次就只有一個可能,所以機率為 3*2*1/3*3*3= 2/9

Q10: 如果-1在這個set裡,那麼-1+2,(-1+2)+2,(-1+2+2)+2都會在這個set裡,至於-3,因為題目只有說N+2在此群組裡,我們也無從得知-5是否在此數列裡,故不能確定-3是否也屬於此數群

Q14:

   我是這樣想的,若10的三次方減去一個二位數(如1000-24),必定只有一個 "9"出現在結果裡,以此類推,10 的50次方減去74,必有50-2個 "9",再加上100-74的值為26,各個位數的總合為 48*9+2+6=440

Q26:

假設X要花a天的時間完成w,Y花a-2天時間完成w,題目說 (w/a+w/a-2)*3=5/4w,解此方程式後可得a=6,那x要做2w所要花的天數即是 2*6=12

Q31:

    這題我是一個一個排除可能,首先所有選項的square root都大概是9...,不到十:99的質因數有11,那不管他與誰相乘都一定大於11,所以排除,97本身即是質因數,相乘絕對大於9,98的質因數裡有2也有7,這兩個相乘就大於9了,95也是,5和19這兩個質因數相乘不可能小於9,至於96,可拆解為2*3*16,所以他的質因數只有2和3, 2*3<9...,所以選這個答案~

謝謝~

atuforever

借问个GWD31和携隐的GWD13有什么区别啊？

xin861123

谢谢~~~~二楼~

xin861123

三楼同学，只知道31是最全的，但有很多重复~~~~