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題目
1. A box contains 100 balls, numbered from 1 to 100.If three balls are selected at random and with replacement from the box, what is the probability that the sum of the three numbers on the balls selected from the box will be odd?
A. 1/4
B. 3/8
C. 1/2
D. 5/8
E. 3/4
答案：C
解析：本題因為奇數和偶數個數相同，和也只有兩種方式，所以三個數的和為奇數的可能性為1/2。也可以考慮從這100個數中任取三個數的奇偶，可能性為：奇奇奇，奇偶偶，奇奇偶和偶偶偶，其中奇奇奇和奇偶偶兩種情況的和為奇數，所以也得到可能性為1/2
2. There are 1200 respondents to a poll, each favoring their preference for candidates A,B, and C. 54% favored A, 48% favored B, and 42% favored C, and there is 30% favored both A and B. What’s the largest possible number of respondents favoring C, but not C&B, nor C&A?
A. 25%
B. 30%
C. 28%
D. 38%
E. 40%
答案：C
解析：A和B的並集為：54%+48%-30%=72%，所C為28%
3. In an insurance company, each policy has a paper record and an electric record. For those policies having incorrect paper record, 60% also having incorrect electric record; For policies having incorrect electric record, 75% also having incorrect paper record.3% of all policies have both incorrect paper and incorrect electric records. If we randomly pick out one policy, what’s the probability that the one having both correct paper and correct electric records?
A. 0.80
B. 0.94
C. 0.75
D. 0.88
E. 0.92
答案：B
解析：設總數為x，設incorrect paper record有y, incorrect electric record有z，則：
x·y·60%=3%·x y=5%
x·z·75%=3%·x z=4%
則，兩者至少有一個錯誤的百分比為5%+4%-3%=6%，所正確答案為94%
4. If Bob can do a job in 20 days and Jane can do the job in 30 days, they work together to do this job and in this period, Bob stop work for 2.5 days and Jane stop work for x days, and the job be finished for 14 days, what is x?
A. 1.6
B. 3.2
C. 1.5
D. 1.25
E. 1.15
答案：D
解析：1/20(14-2.5)+1/30(14-x)=1，得出x=1.25
5. The probability of A is 60% and the probability of B is 50%, what is the most possible probability that neither A nor B would happen?
A. 0.80
B. 0.40
C. 0.75
D. 0.55
E. 0.68
答案：B
解析：劃出圖表來可以一目了然：A， B均不發生的最大機率為40%，最小機率為0.因此選B
GRE機經欄目推薦：
2016GRE全國成績查詢
2016年GRE考試時間表
2016年GRE考試真題及答案匯總
題目
1. A box contains 100 balls, numbered from 1 to 100.If three balls are selected at random and with replacement from the box, what is the probability that the sum of the three numbers on the balls selected from the box will be odd?
A. 1/4
B. 3/8
C. 1/2
D. 5/8
E. 3/4
答案：C
解析：本題因為奇數和偶數個數相同，和也只有兩種方式，所以三個數的和為奇數的可能性為1/2。也可以考慮從這100個數中任取三個數的奇偶，可能性為：奇奇奇，奇偶偶，奇奇偶和偶偶偶，其中奇奇奇和奇偶偶兩種情況的和為奇數，所以也得到可能性為1/2
2. There are 1200 respondents to a poll, each favoring their preference for candidates A,B, and C. 54% favored A, 48% favored B, and 42% favored C, and there is 30% favored both A and B. What’s the largest possible number of respondents favoring C, but not C&B, nor C&A?
A. 25%
B. 30%
C. 28%
D. 38%
E. 40%
答案：C
解析：A和B的並集為：54%+48%-30%=72%，所C為28%
3. In an insurance company, each policy has a paper record and an electric record. For those policies having incorrect paper record, 60% also having incorrect electric record; For policies having incorrect electric record, 75% also having incorrect paper record.3% of all policies have both incorrect paper and incorrect electric records. If we randomly pick out one policy, what’s the probability that the one having both correct paper and correct electric records?
A. 0.80
B. 0.94
C. 0.75
D. 0.88
E. 0.92
答案：B
解析：設總數為x，設incorrect paper record有y, incorrect electric record有z，則：
x·y·60%=3%·x y=5%
x·z·75%=3%·x z=4%
則，兩者至少有一個錯誤的百分比為5%+4%-3%=6%，所正確答案為94%
4. If Bob can do a job in 20 days and Jane can do the job in 30 days, they work together to do this job and in this period, Bob stop work for 2.5 days and Jane stop work for x days, and the job be finished for 14 days, what is x?
A. 1.6
B. 3.2
C. 1.5
D. 1.25
E. 1.15
答案：D
解析：1/20(14-2.5)+1/30(14-x)=1，得出x=1.25
5. The probability of A is 60% and the probability of B is 50%, what is the most possible probability that neither A nor B would happen?
A. 0.80
B. 0.40
C. 0.75
D. 0.55
E. 0.68
答案：B
解析：劃出圖表來可以一目了然：A， B均不發生的最大機率為40%，最小機率為0.因此選B
GRE機經欄目推薦：
2016GRE全國成績查詢
2016年GRE考試時間表
2016年GRE考試真題及答案匯總
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