【单选题】【消耗次数:1】
从一个二项分布总体中抽取容量为100的随机样本,则样本均值的抽样分布近似服从
二项分布
正态分布
卡方分布
F分布
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相关题目
【单选题】 设X服从二项分布,EX=2.4,DX=1.44,则二项分布的参数为
①  n=6,p=0.4
②  n=6,p=0.2
③  n=8,p=0.3
④  n=12,p=0.4
【单选题】 二项分布是指
①  计量资料的分布
②  等级资料的分布
③  离散型随机变量的分布
④  连续型资料的分布
⑤  多项分布资料的分布
【判断题】 当样本量n→∞时,二项分布以泊松分布为极限形式。
①  正确
②  错误
【判断题】 当n<50,nπ和n(1-π)均小于5时,二项分布分布接近正态分布
①  正确
②  错误
【判断题】 随机向量(X,Y)服从二元正态分布,则X的边际分布为正态分布,Y的边际分布也为正态分布.
①  正确
②  错误
【判断题】 随机变量(X,Y)服从二维正态分布,则 X 的边际分布为正态分布,Y的边际分布 也为正态分布
①  正确
②  错误
【判断题】 若X服从二项分布b(k;n,p), 则EX=p
①  正确
②  错误
【判断题】 若X服从二项分布B(5,0.2),则EX=2
①  正确
②  错误
【判断题】 若X服从二项分布b(n,p), 则EX=p.
①  正确
②  错误
【判断题】 若X服从二项分布b(n,p), 则EX=np.
①  正确
②  错误
随机题目
【单选题】 What are not good rules to follow for making instructions effective?
①  Use simple instructions and make them suit the comprehension level of the students
②  Use the mother tongue only when it is necessary
③  Use body language to assist understanding
④  Not model the task or activity before letting students move into groups or pairs .
【单选题】 What role does a teacher play in the following activity? When the students have in groups decided where to go for a spring outing, the teacher asks each group to tell the others why they have made such a choice.
①  Controller
②  Assessor
③  Organizer
④  Prompter.
【单选题】 What role does a teacher play in the following activity? The teacher asks students to produce conversations (either orally or in writing) by using particular patterns or expressions they have just learned.
①  Controller
②  Assessor
③  Organizer
④  Prompter.
【单选题】 What role does a teacher play in the following activity? When students are doing a group-work task, the teacher joins one or two groups for a short period of time.
①  Controller
②  Assessor
③  participant
④  Resource-provider.
【单选题】 What role does a teacher play in the following activity? The teacher has a word in his mind and asks students to guess by asking only Yes/No questions until they make the correct guess.
①  Controller
②  Assessor
③  participant
④  Resource-provider.
【单选题】 Which of the following is the advantage of pair work?
①  It is an ideal way to show materials and do presentations together
②  It allows students to work together rather than under teacher’s guidance
③  It reinforces a sense of belonging among a group of members
④  It is very stressful.
【单选题】 Which of the following is the time when students work in a pair?
①  When all the students are under the control of the teacher
②  When students work in pairs on an exercise or a task
③  When students work in small groups
④  When students are expected to work on their own at their own speed.
【单选题】 What role does a teacher play in the following activity? The teacher writes one of five numbers (1-5) on a number of cards (the same number as the students). Each student draws one card. Those who have drawn number 1 will form group1, and those who have drawn number 2 will form group 2. Thus the students are put into five groups in a random way.
①  Controller
②  Assessor
③  Organizer
④  Prompter.
【单选题】 What are language contents?
①  Structures, vocabulary, functions and topics
②  Pictures, vocabulary, communication and topics
③  PPT, structures, aims and summary
④  Structures, aims, functions and topics.
【单选题】 Which part is to be finished after a lesson in a lesson plan?
①  Teaching aids
②  End of a lesson summary
③  Optional activities and assignment
④  After lesson reflection.