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CIE 9231 2024 June Paper 41 Q7

A Level / CIE / FS

CIE 9231 2024 June Paper 41 Paper · Question 7

题目

Problem

The continuous random variable XX has probability density function ff given by

f(x)={x4(4x2),0x2,0,otherwise.f(x) = \begin{cases} \dfrac{x}{4}(4 - x^2), & 0 \leq x \leq 2, \\ 0, & \text{otherwise.} \end{cases}

(a) Find Var(X)\operatorname{Var}(\sqrt{X}).

[4]

The continuous random variable YY is defined by Y=X2Y = X^2.

(b) Find the probability density function of YY.

[4]

(c) Find the exact value of the median of YY.

[2]
题目中文翻译

连续随机变量 XX 的概率密度函数 ff

f(x)={x4(4x2),0x2,0,otherwise.f(x) = \begin{cases} \dfrac{x}{4}(4 - x^2), & 0 \leq x \leq 2, \\ 0, & \text{otherwise.} \end{cases}

(a) 求 Var(X)\operatorname{Var}(\sqrt{X})

连续随机变量 YY 定义为 Y=X2Y = X^2

(b) 求 YY 的概率密度函数。

(c) 求 YY 的中位数的精确值。

解答