If x1, x2, . . . , xn are independent and identically distributed random variables having uniform distributions over (0, 1), find (a) e[max(x1, . . . , xn)]; (b) e[min(x1, . . . , xn)].

Answers

Answer 1
Answer: Denote by X_((n)) the maximum order statistic, with X_((n))=\max\{X_1,\ldots,X_n\}, and similarly denote by X_((1)) the minimum order statistic. Then the CDF for X_((n)) is

F_{X_((n))}(x)=\mathbb P(X_((n))\le x)

In order for there to be some x that exceeds the value of X_((n)), it must be true that x exceeds the value of all the X_i, so the above is equivalent to the joint probability


F_{X_((n))}(x)=\mathbb P(X_1\le x,\ldots,X_n\le x)

and since the X_i are i.i.d., we have

F_{X_((n))}(x)=\mathbb P(X_1\le x)\cdots\mathbb P(X_n\le x)=\mathbb P(X_1\le x)^n
\implies F_{X_((n))}(x)=F_X(x)^n

where X\sim\mathrm{Unif}(0,1). We have


F_X(x)=\begin{cases}0&\text{for }x<0\nx&\text{for }0\le x\le1\n1&\text{for }x>1\end{cases}

and so

F_{X_((n))}(x)=\begin{cases}0&\text{for }x<0\nx^n&\text{for }0\le x\le1\n1&\text{for }x>1\end{cases}
\implies f_{X_((n))}(x)=\begin{cases}nx^(n-1)&\text{for }0<x<1\n0&\text{otherwise}\end{cases}
\implies\mathbb E[X_((n))]=\displaystyle\int_0^1xnx^(n-1)\,\mathrm dx=n\int_0^1x^n\,\mathrm dx=\frac n{n+1}

Using similar reasoning, we can find the CDF for X_((1)). We have

F_{X_((1))}(x)=\mathbb P(X_((1))\le x)=1-\mathbb P(X_((1))>x)
F_{X_((1))}(x)=1-\mathbb P(X_1>x,\ldots,X_n>x)=1-\mathbb P(X_1>x)^n
F_{X_((1))}(x)=1-(1-\mathbb P(X\le x))^n=1-(1-F_X(x))^n
\implies F_{X_((1))}(x)=\begin{cases}0&\text{for }x<0\n1-(1-x)^n&\text{for }0\le x\le1\n1&\text{for }x>1\end{cases}
\implies f_{X_((1))}(x)=\begin{cases}n(1-x)^(n-1)&\text{for }0<x<1\n0&\text{otherwise}\end{cases}
\implies\mathbb E[X_((1))]=\displaystyle\int_0^1xn(1-x)^(n-1)\,\mathrm dx=\frac1{n+1}
Answer 2
Answer:

Final answer:

The expected values of the maximum and minimum of independent and identically distributed (iid) uniform random variables, x1, x2, ..., xn, are given by E[max(x1, ..., xn)] = n / (n + 1) and E[min(x1, ..., xn)] = 1 / (n + 1) respectively.

Explanation:

In mathematics, particularly in probability theory and statistics, the question is related to independent and identically distributed (iid) random variables with a uniform distribution. The expected value or mean (E) of the maximum (max) and minimum (min) of these random variables is sought.

(a) The expected value of the max of 'n' iid uniform random variables, x1, x2, ..., xn, is calculated by integrating the nth power of x from 0 to 1. It can be found via the equation E[max(x1, ..., xn)] = n / (n + 1).

(b) Similarly, the expected value of the min of 'n' iid uniform random variables is acquired by doing (1 / (n + 1)). Hence, E[min(x1, ..., xn)] = 1 / (n + 1).

By understanding these, you could visualize the various outcomes of the random variables and their distributions, demonstrating how likely each outcome could occur.

Learn more about the Expected Value of Random Variables here:

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Answers

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Answer:

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Step-by-step explanation:

The volume formula is ...

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Answers

Answer:

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Step-by-step explanation:

first do the parenthesis and do -1 * 7x and -1 * -2

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3x - 7x and the 2+2= 4x+4

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Answers

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Step-by-step explanation:


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Answers

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Step-by-step explanation:

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Answers

Answer:

1/6y+1/6(y+12)- 2

Step-by-step explanation:

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Answer:

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Answers

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