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數學功課!!!緊急>.< (c) and(d)必答!!!20

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Alex is a salesperson. the following is the probability distribution funtion of the number of customers he meets in a day,X.以下係table formatx 0 1 2 3 4P(X=x) 0 3c 2c c c(a)What is the value of c?(b)what are the ecpected value and... 顯示更多 Alex is a salesperson. the following is the probability distribution funtion of the number of customers he meets in a day,X. 以下係table format x 0 1 2 3 4 P(X=x) 0 3c 2c c c (a)What is the value of c? (b)what are the ecpected value and standard deviation of X? Suppose Alex works from Monday to Friday in a week. it is assumed that the numbers of customers he meets each day are independent. (c)What are the ecpected value and standard deviation of Y, where Y is the number of customers he meets in a week? (d)What is the probability that he meets exactly five customers in a week??

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Alex is a salesperson. the following is the probability distribution funtion of the number of customers he meets in a day,X.Table format:x 0 1 2 3 4P(x) 0 3c 2c c c(a)What is the value of c?3c+2c+c+c=1 => c=1/7.....ans (b)what are the expected value and standard deviation of X?E(x)=Xbar=(0+1+2+3+4)/5=2.......ansVar(x)=Σx^2/n-Xbar^2=(1+4+9+16)/5-4=29/5-4=9/5Std=√Var=3√5/5...........ans Suppose Alex works from Monday to Friday in a week. It is assumed that the numbers of customers he meets each day are independent.(c)What are the expected value and standard deviation of Y, where Y is the number of customers he meets in a week?Ybar=(0+5+10+15+20)/5=10......ansVar(Y)=Σy^2/n-Ybar^2=(25+100+225+400)/5-100=150-100=50Std(Y)=√Var(Y)=5√2........ans (d)What is the probability that he meets exactly five customers in a week?y=(0,5,10,15,20)P(y)=(0,3c,2c,c,c)P(y=5)=3c=3/7......ans

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