4月gre考试辅导:2013gre数学备考5道练习题及答案
1. 从1,2,3,4,5,6,7,8,9中选出三个数字组成一个三位数,这个三位数的digits中有两个相同,另一个digit与其它两个都不同,问共有多少个这样的三位数? (A) 72 (B) 144 (C) 180 (D) 216 (E) 54 2.符合 X^2+Y^2<=100的整数解共有多少对? 3.A box contains 100 balls, numbered from 1 to 100.If three balls are selected at random and with replacement from the box,what is the probability that the sum of the three numbers on the balls selected from the box will be od (A) 1/4 (B) 3/8 (C) 1/2 (D) 5/8 (E) 3/4 4.Right triangle PQR is to be constructed in the xy-plane so that the right angle is at P and PR is parrallel to ... [ 查看全文 ]4月gre考试辅导:2013gre数学备考5道练习题及答案的相关文章