小伙伴们，大家GMAT考试备考的怎么样了呢？下面帮考网分享了一些机经的练习题，一起来看看吧！

数学机经

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：本题因为奇数和偶数个数相同，和也叧有两种方式，所以三个数的和为奇数的可能性为1/2。也可以考虑从这100个数中获取三个数的奇偶，可能性为：奇奇奇，奇偶偶，奇奇偶和偶偶偶，其中奇奇奇和奇偶偶两种情况的和为奇数，所以也得到可能性为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的并集为：54%+48%-30%=72%，所C为 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：设总数为 x设incorrect paper record有y, incorrect electric record 有z，则：x·y·60%=3%·x y=5% x·z·75%=3%·x z=4%则，两者至少有一个错误的百分比为 5%+4%-3%=6%，所正确答案为 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：划出图表来可以一目了然：A， B 均丌发生癿最大概率为 40%，最小概率为0.因此选 B

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