已选分类
理学数学
单选题m is a two digit number (位数) and 2m is a three digit number (三位数)，what is the unit digit (个位) of m? (1)the unit number of 2m is 4 (2)the unit number of m is the same as the tens number (十位数) of 2m
单选题一枚硬币(coin)，若投一次正面朝上的概率不是0.5，则是多少?(1)正面朝上的概率是正面朝下的概率的两倍。(2)连续投两次，一次朝上一次朝下的概率是。(A)条件(1)充分，但条件(2)不充分．(B)条件(2)充分，但条件(1)不充分．(C)条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．(D)条件(1)充分，条件(2)也充分．(E)条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．
单选题有三个盛有酒精的容器，如果把甲容器内的溶液倒入乙容器，再把乙容器内的溶液倒入丙容器，最后把丙容器内的溶液倒入甲容器，这时甲、乙、丙三个容器里的酒精都是9千克，则甲容器中原有酒精______千克．A．12B．10C．9D．8
单选题已知某数列中共有7个数，其中数(median)为100，值域(range)为50。其中最小的三个数的中数为70，问最大的三个数的值域(range)可能是多少? Ⅰ．0 Ⅱ．20 Ⅲ．40
单选题To fill a number of vacancies, an employer must hire 3 programmers from among 6 applicants, and 2 managers from among 4 applicants. What is the total number of ways in which she can make her selection?
单选题设矩阵A满足A2+A-4E=0，其中E为单位矩阵，则A-E的逆阵为______。A．A-2EB．A+2EC．(A-2E)D．(A+2E)
单选题S是一个数列(A1, A2, …, An)，问数列S的标准方差是多少? (1)每个数相等。 (2)该数列的算术平均数是7。
单选题A computer is programmed to generate a list of multiples of prime numbers 2, 3, and 5, as shown below： Program 1-List multiples of 2 Program 2-List multiples of 3 Program 3-list multiples of 5 How many integers between 1 and 100 will appear on all three of the lists of the programs produced above?
单选题对于任意两个随机变量X，Y，若E(XY)=E(X)·E(Y)，则______。
A.D(XY)=D(X)·D(Y)
B.D(X+Y)=D(X)+D(Y)
C.X，Y相互独立
D.X，Y不独立
单选题
单选题有一组数是0，9，5，X，Y，其中X，Y是正数，问这组数的值域(range)是多少? (1)X+Y=9 (2)X+Y=1
单选题一个三位数的百位数是多少? (1)该三位数加上150后所得新数的百位数是4 (2)该三位数加上150后所得新数的十位数是5
单选题三位教师分配到6个班级任教，若其中一人教1个班，一人教2个班，一人教3个班，则共有分配方法( )． A．720种 B．360种 C．120种 D．60种 E．56种
单选题已知ABCD为四边形，边长AB=12，DA=5，问：ABCD是否为矩形? (1)对角线DB=13 (2)AB=DC，且AD=BC (A) 条件(1)充分，但条件(2)不充分． (B) 条件(2)充分，但条件(1)不充分． (C) 条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分． (D) 条件(1)充分，条件(2)也充分． (E) 条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．
单选题若方程x2+px+q=0的一个根是另一个根的2倍．则P和q应满足( )． A．p2=4q B．2p=3q2 C．4p=9q2 D．2p2=9q E．以上结论均不正确
单选题John budgeted 50% of his take-home pay for household expense, 20% for transportation, 15% for a retirement fund, and the remaining $240 for recreation. How much of his take home pay did he budget for household expenses? (A) $500 (B) $800 (C) $1,000 (D) $1,200 (E) $240
单选题菜园里的白菜获得丰收，收到时，装满4筐还多24斤，其余部分收完后刚好又装满了8筐，菜园共收获了白菜()．A．381斤B．382斤C．383斤D．384斤E．385斤
单选题设二维随机变量(X，Y)的联合分布律为已知E(XY)=0.8，则P{X＞2Y}=______。A.0.7B.0.6C.0.5D.0.4
单选题A first-grade teacher use ten flash cards, numbered 1 through 10, to teach her students to order numbers correctly. She has students choose four flash cards randomly, then arrange the cards in ascending order. One day, she removes the cards numbered "2" and "4" from the deck of flash cards. On that day, how many different correct arrangements of four randomly selected cards are possible? (A) 70 (B) 210 (C) 336 (D) 840 (E) 1,680
单选题若b＜0，0＜|a|＜|b|＜|c|，且，则必有______．A．c＜b＜aB．a＜b＜cC．b＜a＜cD．b＜c＜a