8.设{an}是等差数列,{bn}为等比数列,其公比q≠1,且bi>0(i=1,2,3,…,n),若a1=b1,a13=b13,则有( )
| A. | a7=b7 | B. | a7>b7或a7<b7 | C. | a7<b7 | D. | a7>b7 |
7.不等式(x-2)(3-x)>0的解集是( )
| A. | {x|x<2或x>3} | B. | {x|2<x<3} | C. | {x|x<2} | D. | {x|x>3} |
6.现从编号为1~31的31台机器中,用系统抽样法抽取3台,测试其性能,则抽出的编号可能为( )
0 240682 240690 240696 240700 240706 240708 240712 240718 240720 240726 240732 240736 240738 240742 240748 240750 240756 240760 240762 240766 240768 240772 240774 240776 240777 240778 240780 240781 240782 240784 240786 240790 240792 240796 240798 240802 240808 240810 240816 240820 240822 240826 240832 240838 240840 240846 240850 240852 240858 240862 240868 240876 266669
| A. | 4,9,14 | B. | 4,6,12 | C. | 2,11,20 | D. | 3,13,23 |