GRE数学练习题及答案解析分享，一起来了解一下。
1、What is the least positive integer that is not a factor of 25! and is not a prime number?
A 26
B 28
C 36
D 56
E 58
这个题，你看25!里面包括了2到25的所有factor了，所以你看26=2*13,28=2*14,36=2*18,56=7*8，而只有58=2*29,29不在里面，所以就选这个了
2、The fabric needed to make 3 curtains sells for $8.00 per yard and can be purchased only by the full yard. If the length of fabric required for each curtain is 1.6 yards and all of the fabric is purchased as a single length, what is the total cost of the fabric that needs to be purchased for the 3 curtains?
A $40.00
B $38.40
C $24.00
D $16.00
E $12.80
Since 1.6 yards of fabric are required for each curtain, it follows that (3)(1.6), or 4.8, yards of fabric are required to make the 3 curtains. The fabric can be purchased only by the full yard, so 5 yards of fabric would need to be purchased.
Since the fabric sells for $8.00 per yard, the total cost of the fabric is $40.00. The correct answer is Choice A.
还是用汉语解释下吧，一共三个窗帘，每个1.6m，那么一共要4.8m，由于不能零卖，只能整数的卖，所以买5m，一共是5*8=40了。
3、Which of the following statements individually provide(s) sufficient additional information to determine the area of triangle ABC above? Indicate all such statements.
A DBC is an equilateral triangle.
B ABD is an isosceles triangle.
C The length of BC is equal to the length of AD.
D The length of BC is 10.
E The length of AD is 10
只告诉了三角形是直角三角形和一条直角边，要求我们补充条件可以求得三角形的面积。只能用排除法。A说三角形DBC是等边的，角C就是60度了，其他的便也就可以求出来了，面积就可以求。B说ABD是等腰三角形，这个没意义，因为没说那两个边是等的，比如如果AB=AD，是没法求的，C说BC=AD，这个条件是没有意义的，因为我们的D点可以移动，当三角形的大小发生变化时，我们总可以找到对应的D点使得AD=BC，D选项说BC=10，这就可以求了，E说AD的长是10，这个同样没意义。所以选AD。