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Probability

Continuous Random Variables

Concept Quizzes

Continuous Random Variables - Probability Density Function (PDF)
Continuous Random Variables - Cumulative Distribution Function
Higher Moments Warmup
Continuous Random Variables - Joint Probability Distribution
Continuous Random Variables - Problem Solving

Continuous Random Variables - Joint Probability Distribution

Let $X$ and $Y$ have the joint probability density function: $f(x,y)=\frac{1}{49}xy$ for $0\leq x\leq2$ and $0\leq y\leq7.$ Find the expected value of $3X.$

2 7 14 4

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by Brilliant Staff

Let $X$ and $Y$ have the joint probability density function: $f(x,y)=k(x+y)$ for $0\leq x\leq10$ and $0\leq y\leq1,$ where $k$ is a constant. Find the marginal probability $P(1\leq X\leq2).$

\frac{2}{55}

\frac{1}{10}

\frac{3}{55}

\frac{3}{20}

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by Brilliant Staff

Let $X$ and $Y$ have the joint probability density function: $f(x,y)=k$ for $0\leq x\leq5$ and $0\leq y\leq8,$ where $k$ is a constant. Find the covariance between $X$ and $Y.$

\frac{8}{5}

0

\frac{5}{8}

{3}

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by Brilliant Staff

Let $X$ and $Y$ have the joint probability density function: $f(x,y)=kxy$ for $0\leq x\leq4$ and $0\leq y\leq3,$ where $k$ is a constant. Find $P(X < Y).$

\frac{4}{3}

\frac{23}{32}

\frac{8}{9}

\frac{9}{32}

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by Brilliant Staff

Which of the following CANNOT be the joint probability density function of two continuous random variables $X$ and $Y?$

(A): $f(x,y)=1$ for $0\leq x,y\leq1.$

(B): $f(x,y)=x+y$ for $0\leq x,y\leq1.$

(C): $f(x,y)=xy$ for $0\leq x,y\leq1.$

(D): $f(x,y)=e^{x+y}$ for $0\leq x,y\leq\ln2.$

(A)

(B)

(C)

(D)

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by Brilliant Staff