1、GRE（ QUANTITATIVE）练习试卷 18及答案与解析 1 3x-17=46. Solve for x. 2 x/4=-6. Solve for x. 3 If x=15, then 4x- _ =42 4 Two trains running on parallel tracks are 600 miles apart. One train is moving east at a speed of 90 mph, while the other is moving west at 75 mph. How long will it take for the two trains to
2、pass each other? 5 3(x-4)=5x-20. Solve for x. GRE（ QUANTITATIVE）练习试卷 18答案与解析 1 【正确答案】 To solve this problem, first isolate the unknown number on one side. To do this, add 17 to both sides to get 3x=63. Next, divide both sides by 3 to isolate the x on the left side: x=21. 2 【正确答案】 To solve this probl
3、em, multiply both sides by 4 to get rid of the fraction and isolate the x on the left side: x=-24. 3 【正确答案】 You are given the value of x, and asked to calculate a missing number in the equation. Because x=15, then 4x=60. The equation is now 60-(some number)=42. The difference between 60 and 42 is 18
4、. 4 【正确答案】 This is a standard RateTime=Distance problem. Since the two trains start 600 miles apart, the combined distance traveled by both trains must equal 600. Using the RT=D formula, you know that (Rate of Train 1Time of Train 1)+(Rate of Train 2Time of Train 2)=600. You are given that the rate
5、of travel is 90 mph for the first train and 75 mph for the second train, and the distance traveled is 600 miles; therefore, you must solve for T, as follows: 90T+75T=600 165T=600 T=(approximately) 3.64 hours 5 【正确答案】 To solve this problem, first do the multiplication on the left side of the equation to get 3x-12=5x-20. Next, put the like terms together. To do this, subtract 3x from both sides, and add 20 to both sides to get 8=2x. Divide both sides by 2 to get x=4.
