为了便于大家更好的进行
1、P, Q, and R are three points in a plane, and R does not lie on line PQ. Which of the following is true about the set of all points in the plane that are the same distance from all three points?
A. It contains no points.
B. It contains one point.
C. It contains two points.
D. It is a line.
E. It is a circle.
答案：B
解析：两条相连线段的中线只有一个焦点，到P和Q两点相同的点必定PQ的垂直平分线上， 到P和R两点相同的点也必定在PR的垂直平分线上，由于R不在PQ上，说明PQ的垂直平分线和PR的垂直平分线不平行，相交于一点，这一点到这PQR三点的距离相等，其实就是确定了一个圆心，不在一条直线上的三点确定一个圆。
2、If the product of 7 consecutive integers is equal to the median of the integers, what is the least of the 7 integers?
答案：-3
解析：这个题要多思考，连续7个整数的乘积是中数，则中数一定是0，这样乘积也是0。然后再根据
consecutive倒推，得知最小的数字是-3。
3、In a data set of 10,000 numbers varying from 20 to 80, the number 62 is the 60th percentile and the number 74 is the nth percentile.
Quantity A：n
Quantity B： 70
A. Quantity A is greater.
B. Quantity B is greater.
C. The two quantities are equal.
D. The relationship cannot be determined from the information given.
答案：D
解析：注意这个题没有说这10000个数字是均匀分布的，所以nth 和70的大小是无法比较的。
4、A box at a yard sale contains 3 different china dinner set, each consisting of 5 plates. A
customer will randomly select 2 plates to check for defects. What is the probability that the 2 plates
selected will be from the same dinner set?
A. 2/7
B. 2/5
C. 2/3
D. 5/6
E. 3/2
答案：A
解析：分子的表达方式是从5个盘子中选2个，一共有10种选法，然后有3个不同的set，所以再乘以3，所以分子是30，分母是从15个盘子中选2个，算出来是105，所以最终答案是30/105=2/7。
5、If 2, 4, 6, 9 are the digits of two 2-digit integers, what is the least possible positive difference between the integers?
A. 28 B. 27 C. 17 D. 13 E. 9
答案：D
解析：此题可以用带入求值的方法来进行计算，可知当一个数是49，另外一个数字是62的时候，两个数字的差为13，是最小的。