下面小编跟大家一起了解GMAT数学机经讲解练习，希望对大家的学习有所帮助。
　　135 DS：质因数
　　If x and y are positive integers, is 18 a factor of x*(?2)？
　　（1）x is amultiple of 54
　　（2）y = 6
　　136 PS：比例计算
　　一个景点统计游客的国籍比例。
　　80%的游客来自于美国；剩下的 20%的游客中，有 50%来自于加拿大或墨西哥；既不
　　来自于美国也不来自于加拿大、墨西哥的人中，有 50%来自欧洲，问美国参观者数量
　　是欧洲的多少倍？
　　1.In a certain game, the units of currency of three countries are the crown, the shield, and the pound, respectively. If 2 crowns equal 3 shields and 3 shields equal 4 pounds, how many crowns equal 18 pounds?
　　（A）9 (B) 16 (C) 18 (D) 32 (E) 36
　　2.
　　38, 69, 22, 73, 31, 47, 13, 82
　　Which of the following numbers is greater than three-fourths of the numbers but less than one-fourth of the numbers in the list above?
　　(A) 56
　　(B) 68
　　(C) 69
　　(D) 71
　　(E) 73
　　3.If x^4 y^4 = 100, then the greatest possible value of x is between
　　(A) 0 and 3
　　(B) 3 and 6
　　(C) 6 and 9
　　(D) 9 and 12
　　(E) 12 and 15
　　4.A company has two types of machines, type R and type S. Operating at a constant rate, a machine of type R does a certain job in 36 hours and a machine of type S does the same job in 18 hours. If the company used the same number of each type of machine to do the job in 2 hours,
　　how many machines of type R were used?
　　(A) 3
　　(B) 4
　　(C) 6
　　(D) 9
　　(E) 12
　　5. If x is a negative integer, which of the following expressions has the LEAST value?
　　(A) X^2 —0.50
　　(B) X^2—0.51
　　(C) X^3—0.502
　　(D) X^3— 0.511
　　(E) X^4—0.512
　　6. A boat traveled upstream a distance of 90 miles at an average speed of (v - 3) miles per hour and then traveled the same distance downstream at an average speed of (v 3) miles per hour.
　　If the trip upstream took half an hour longer than the trip downstream, how many hours did it take the boat to travel downstream?
　　(A) 2.5
　　(B) 2.4
　　(C) 2.3
　　(D) 2.2
　　(E) 2.1
　　7. If 75 percent of a class answered the first question on a certain test correctly, 55 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percent answered both correctly?
　　(A) 10%
　　(B) 20%
　　(C) 30%
　　(D) 50%
　　(E) 65%
　　8.The cost of delivery for an order of desk chairs was $10 for the first chair, and1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n > 24 ?
　　(1)The delivery cost for the order totaled more than $30.00.
　　(2) The average (arithmetic mean) delivery cost per chair of the n chairs was $1.36.