Functions of a Random Variable

Finding the CDF of a Continuous Random Variable Y based on a function of X

  • A graph of (Y=g(X))(Y = g(X)) is shown, and a random point (yi)(y_i) is chosen on the y-axis.
  • Your goal is to construct the formula for the CDF of YY at that point, (FY(yi)=P(Yyi))(F_Y(y_i) = P(Y \le y_i)).
  • First, find the setofall x-values for which (g(X)yi)(g(X) \le y_i).
  • Then, express the probability of this setusing the CDF of XX, (FX(x))(F_X(x)).

Visualize PDF of a Function of RV

  • Let XX be a Uniform random variable on [-1, 1]. Its PDF is shown in the first graph.
  • Select a function to visualize: Quadratic (Z=X2)(Z = X^2) or Exponential (Z=eX)(Z = e^X).
  • Three graphs will appear, the transformation function (g(X))(g(X)), the original PDF of X, and the resulting PDF of ZZ.
  • Click on the PDF of ZZ graph to highlight a region.
  • Alternatively, type a start and end value in the Highlight ZZ Range panel to see the charts update in real-time.

Calculate PDF of a function of multiple RVs

  • Two problems are provided. Use the Next and Prev buttons to switch between them.
  • Press START to begin. You will be prompted to enter the value of the PDF, (fZ(z))(f_Z(z)), for 5 random values of (z)(z).
  • Submit each value by clicking the button or pressing Enter. Your point will be plotted on the graph.
  • Once all 5 points are entered, the complete, correct PDF of ZZ will be plotted for comparison.