1、GRE（ QUANTITATIVE）计算题模拟试卷 2及答案与解析 1 33 =_ 2 22 23 =_ 3 125 = 5_ 4 (24)2=_ 5 423,700,000 = 4.237 10 to the power of_ 6 3.76 105=_ 7 (2.50 104)+(1.25 103)=_ 8 6.4710-5 =_ 9 9.832104 =_ 10 Ann scored 88, 93, 84, and 99 on 4 tests. What is her mean test score? 11 What is the mode of the data given below
2、? 7, 3, 6, 7, 5, 8, 9, 7 12 What is the median of the data given below? 8, 13,9,8, 15, 14, 10 13 Jordan had 3 hits in his first 4 baseball games and 4 hits in his next 4 games. What is the average number of hits Jordan had in all of his games? 14 What is the median of the data given below? 80,19,82,
3、 15, 72, 3 15 _is 30% of 20. 16 x/6=39/78 What is the value of x? 17 As an analyst for the Department of Natural Resources, you analyze samples of river water. A 2-liter sample of water contained about 24 of a particular organism and a 4-liter sample of water contained about 48 such organisms. At th
4、is rate, how many of the organisms would you expect to find in a 10-liter sample of water from the same river? 18 If 20% of x equals 16, then x =_ 19 Jim scored 95 points in 5 basketball games for his school. At this rate, how many points will he have scored by the end of the 12-game season? 20 If x
5、 = -8, what is the value of | x - 6 ? 21 Solve |4x- 6 = 10 for x. 22 | -15 | 6 | =_ 23 Solve 6x + 8 = 3x - 7 for x. 24 =_ 25 If you roll a single 6-sided die, what is the probability that you will roll an odd number? 26 A company knows that 2.5% of the CD players it makes are defective. If the compa
6、ny produces 300,000 CD players, how many will be defective? 27 When flipping a coin, what is the probability that it will land on tails four times in a row? 28 If the probability that Dave will go to class is 0.7, what is the probability that he will not go to class? 29 A bowl contains 20 marbles(8
7、blue, 6 red, 3 green, 2 yellow, and 1 orange). If you reach in and choose one marble at random, what is the probability that it will be red? 30 A certain integer n is a multiple of both 5 and Must n be a multiple of 15? GRE（ QUANTITATIVE）计算题模拟试卷 2答案与解析 1 【正确答案】 27 【试题解析】 33, or 3 to the third power,
8、 means you must multiply 333, which equals 27. 【知识模块】 计算 2 【正确答案】 32 【试题解析】 Remember to add the exponents when multiplying exponential values with the same base: 22 23 = 25 = 32. 【知识模块】 计算 3 【正确答案】 125 【试题解析】 53 = 5 5 5, which gives you 125. 【知识模块】 计算 4 【正确答案】 256 【试题解析】 When raising an exponent to
9、another power, multiply the exponents(42 = 8). So, the answer is 28, or 256. 【知识模块】 计算 5 【正确答案】 8 【试题解析】 When dealing with scientific notation, the power that 10 is raised to gives you the number of spaces you must move the decimal place, either to the right(for a positive value), or to the left(for
10、 a negative value). To turn 4.237 into 423,700,000, you must move the decimal place 8 spaces to the right. Therefore, 10 needs to be raised to the power of 8(108). 【知识模块】 计算 6 【正确答案】 376000 【试题解析】 To solve this problem, you must simply move the decimal point the number of times indicated by the powe
11、r to which 10 is raised. Since you are given 105, you know that you must move the decimal point 5 spaces to the right, because the exponent is a positive number. This gives an answer of 376,000. 【知识模块】 计算 7 【正确答案】 20 【试题解析】 This problem can be set up as = 2. When dividing like bases, you subtract yo
12、ur exponents, so 104 103= 101. You are left with 2 101. Since 10 to the first power is 10, the correct answer is 20. 【知识模块】 计算 8 【正确答案】 0.0000647 【试题解析】 You are given a negative value for the power to which 10 is raised(-5). This means that you must move the decimal point 5 spaces to the left to get
13、 the answer, which is .0000647. 【知识模块】 计算 9 【正确答案】 98320 【试题解析】 Because 10 is raised to the fourth power, move the decimal point 4 places to the right to get 98,320. 【知识模块】 计算 10 【正确答案】 91 【试题解析】 The mean is the average, so simply add the test scores and divide by 4(the total number of tests): 88 +
14、93 + 84 + 99 = 364 364 4 = 91 【知识模块】 计算 11 【正确答案】 7 【试题解析】 The mode is the number that appears most frequently in a series of numbers. In this case, the mode is 7. 【知识模块】 计算 12 【正确答案】 10 【试题解析】 The median is the middle value in an ordered set of values. Therefore, the first step is to put the number
15、s in order, as follows: 8,8,9,10, 13, 14,15 As you can see, 10 is the middle value. 【知识模块】 计算 13 【正确答案】 3.5 【试题解析】 To calculate Jordans average number of hits, first find his total number of hits: 3 4 - 12 and 4 4 = 16 12 + 16 = 28 Next, find the average: 28 8 = 3.5 【知识模块】 计算 14 【正确答案】 45.5 【试题解析】 T
16、he median is the middle value in an ordered set of values. Therefore, the first step is to put the numbers in order, as follows: 3, 15, 19, 72,80,82 Because the set includes an even number of values, take the average of the middle values: 19 + 72 = 91 91 + 2 = 45.5 【知识模块】 计算 15 【正确答案】 6 【试题解析】 To so
17、lve this problem, set up a proportion. You are looking for a number that is 30% of 20. The proportion will be x/20 = 30/100, because the unknown number is 30% of the whole(20). To solve, cross-multiply, leaving you with 100x = 600. Divide both sides by 100, and you get the final answer: x = 6. 【知识模块
18、】 计算 16 【正确答案】 3 【试题解析】 You are given a proportion to solve. To find the answer, cross-multiply, giving you 78x = 234. Dividing both sides by 78 will give you the answer: x = 3. 【知识模块】 计算 17 【正确答案】 120 【试题解析】 To answer this question you must determine the ratio of organisms to liters of river water.
19、 The problem states that a 2-liter sample of water contained about 24 organisms and a 4-liter sample of water contained about 48 organisms. Upon closer examination of this information you will see that the ratio of organisms to water is the same in each sample. Therefore, you can set up a ratio usin
20、g one sample: 2 liters of water yields 24 organisms. This can be expressed as 2 to 24, or 2:24, which can be reduced to 1:12. For every 1 liter of water you will see 12 organisms. Therefore, 10 liters of water will contain 120 organisms. 【知识模块】 计算 18 【正确答案】 80 【试题解析】 Set up a proportion. You are giv
21、en that 20% of x is equal to 16, and you want to find the value of x. The proportion will look like this: 16/x=20/100 After cross-multiplying, you are left with 20x = 1,600. After dividing both sides by 20, you have the answer: x = 80. 【知识模块】 计算 19 【正确答案】 228 【试题解析】 Use a proportion to solve this pr
22、oblem. You know that Jim scored 95 points in 5 games, and you want to find out how many points he will score in a total of 12 games. The proportion will look like this: 95/5 = x/12 Cross-multiply to get 5x = 1,140. Divide both sides by 5, and you get the answer: x = 228. If Jim continues to score at
23、 this rate, he will score a total of 228 points by the end of the season(12 games). 【知识模块】 计算 20 【正确答案】 14 【试题解析】 First, substitute -8 for x and do the subtraction within the absolute value lines(-8 - 6 = -14). Absolute value is the numerical value of a real number without regard to its sign. Theref
24、ore, the absolute value of-14 is 14. 【知识模块】 计算 21 【正确答案】 -1 【试题解析】 To solve this problem, set up two equations because x has two values: 4x - 6 = 10, and 4x - 6 = -10. Solve both for x. 4x = 16, and 4x = -4 x = 4, and x = - 1 【知识模块】 计算 22 【正确答案】 90 【试题解析】 In order to perform the multiplication in th
25、is problem, first find the absolute value of both numbers. The absolute values of -15 and 6 are 15 and 6, respectively. The answer is 156 = 90. 【知识模块】 计算 23 【正确答案】 -5, -1/9 【试题解析】 To find the possible answers for x in this problem, set up two equations:6x + 8 = 3x - 7, and 6x + 8 = -(3x - 7).First,
26、distribute the minus sign in the second equation, giving you 6x + 8 = -3x + 7. Then solve both for x:3x= -15,and 9x = -1x = -5, and x = - 【知识模块】 计算 24 【正确答案】 -4 【试题解析】 First find the absolute value of the denominator. The absolute value of -8 is 8. Now perform the division: -32 8 = -4. 【知识模块】 计算 25
27、【正确答案】 0.5 【试题解析】 On a 6-sided die, there are 3 even numbers, and 3 odd numbers. Therefore, the probability that you will roll an odd number is 3 out of 6, or3/6. This can be reduced to 1/2, or 0.5. 【知识模块】 计算 26 【正确答案】 7500 【试题解析】 If 2.5% of the CD players produced by this company are defective, the
28、n the number of defective devices out of 300,000 can be determined by multiplication, as follows: 0.025 X 300,000 = 7,500 【知识模块】 计算 27 【正确答案】 1/16 【试题解析】 When flipping a coin, there are only two possible outcomes: heads or tails. Therefore, each side has a probability of 1/2, or .5, of landing facin
29、g up. The chances of the coin landing on tails four times in a row can be expressed as , or = 1/16. 【知识模块】 计算 28 【正确答案】 0.3 【试题解析】 The probability that Dave will go to class is 0.7, or 70%. Therefore, the probability that he will NOT go to class is 100% - 70%, or 30%, which is equivalent to 0.3, so
30、either answer will be correct. 【知识模块】 计算 29 【正确答案】 3/10 【试题解析】 There is a total of 20 marbles in the bowl, 6 of which are red. If one marble is selected at random, the probability that it will be red is This can be reduced to 3/10. 【知识模块】 计算 30 【正确答案】 15 【试题解析】 The first step in solving this problem
31、 is to find the Least Common Multiple(LCM)of 5 and 9. Because a multiple of 5 must have either a 5 or a 0 in the digits place, and 9 5 is the first multiple of 9 with a 5 in the digits place, 9 5 = 45 must be the LCM. Therefore, n must be a multiple of 15, since 45(one possible value of n)is a multiple of 15. 【知识模块】 计算
