Continuous Probability Distributions: Verifying Probability Density Function
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Questions and Answers

What is the value of P(0 < X ≤ 1), given the probability density function f(x) = x^2/3, -1 < x < 2?

  • 2/9 (correct)
  • 1/3
  • 1/6
  • 1/9

What is the cumulative distribution function F(x) of the continuous random variable X with density function f(x) = x^2/3, -1 < x < 2?

  • F(x) = x^3/9, -1 ≤ x ≤ 2 (correct)
  • F(x) = x^2/3, -1 ≤ x ≤ 2
  • F(x) = x^2/3 + 1, -1 ≤ x ≤ 2
  • F(x) = x^3/9 + 1, -1 ≤ x ≤ 2

What is the mean of the random variable X, representing the number of heads in 16 tosses of two coins?

  • 7/16
  • 11/16 (correct)
  • 5
  • 4

What is the nature of the probability density function of a continuous random variable?

<p>It is a non-negative function that integrates to 1 over the entire real line. (D)</p> Signup and view all the answers

What is the purpose of the cumulative distribution function F(x) of a continuous random variable X?

<p>To calculate the probability of a range of values of X (A)</p> Signup and view all the answers

What is the value of μ in the given discrete probability distribution?

<p>0.61 (A)</p> Signup and view all the answers

What is the formula for calculating the variance of a continuous random variable X with probability density function f(x)?

<p>σ² = E(X²) - μ² (B)</p> Signup and view all the answers

What is the formula for calculating the variance of a function g(X) of a discrete random variable X?

<p>σ² = ∑[g(X) - μg(X)]²f(x) (C)</p> Signup and view all the answers

What is the value of E(X) for the continuous random variable X with probability density function f(x) = 2(x-1), 1 < x < 2?

<p>4/3 (D)</p> Signup and view all the answers

What is the formula for calculating the variance of a function g(X) of a continuous random variable X?

<p>σ² = ∫[g(X) - μg(X)]²f(x)dx (C)</p> Signup and view all the answers

What is the value of σ² for the continuous random variable X with probability density function f(x) = 2(x-1), 1 < x < 2?

<p>5/18 (C)</p> Signup and view all the answers

What is the covariance of two random variables X and Y with means μX and μY, respectively?

<p>E[(X - μX)(Y - μY)] (D)</p> Signup and view all the answers

What is the formula for the covariance of discrete random variables X and Y?

<p>∑∑ (x - μX)(y - μY)f(x, y) (A)</p> Signup and view all the answers

What does a negative covariance between X and Y indicate?

<p>A negative correlation between X and Y (A)</p> Signup and view all the answers

What is the covariance of X and Y in the 'ballpoint pens' example?

<p>-56/28 (A)</p> Signup and view all the answers

What is the first step in finding the covariance of X and Y in the 'fraction of runners' example?

<p>Compute the marginal density functions (D)</p> Signup and view all the answers

What is the interpretation of the covariance of X and Y?

<p>The linear relationship between X and Y (A)</p> Signup and view all the answers

What is the term used to describe the long-term average outcome of a given scenario?

<p>Expected value (D)</p> Signup and view all the answers

What is the probability distribution of X in the given scenario, where X is the number of good components in the sample?

<p>f(x) = Cx × 3 / 7C3 (A)</p> Signup and view all the answers

What is the mean or expected value of X if X is a continuous random variable?

<p>μ = E(X) = ∫xf(x)dx from -∞ to ∞ (C)</p> Signup and view all the answers

What is the expected value of the number of good components in the sample of 3?

<p>1.714 (A)</p> Signup and view all the answers

What is the number of defective components in the lot?

<p>3 (D)</p> Signup and view all the answers

If 3 components are selected at random from a lot of 4 good components and 3 defective components, what is the average number of bad components that one will pick?

<p>1.3 (A)</p> Signup and view all the answers

What is the variance of the random variable Z = 3X – 2Y + 5 when X and Y are independent random variables with variances σX2 = 2 and σY2 = 3?

<p>30 (C)</p> Signup and view all the answers

What is the joint probability distribution of two discrete random variables X and Y?

<p>A joint probability distribution function (A)</p> Signup and view all the answers

What is the relationship between the random variables X and Y in the given problem?

<p>They are independent random variables (D)</p> Signup and view all the answers

What is the value of Z2 = 3X – 2Y + 5 when X and Y are independent random variables with variances σX2 = 2 and σY2 = 3?

<p>30 (B)</p> Signup and view all the answers

What is the purpose of the moment-generating function in joint probability distributions?

<p>To find the moment-generating function of the joint distribution (C)</p> Signup and view all the answers

What is the chapter that discusses the joint probability distribution of two random variables?

<p>Chapter 5 (A)</p> Signup and view all the answers

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