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12.4 Exercise 32

Avg difficulty 2.5

fXY(t,u)=388(2t+3u2)f_{X Y} \left(t , u\right) = \frac{3}{88} \left(2 t + 3 u^{2}\right) for 0≤t≤20 \leq t \leq 2, 0≤u≤1+t0 \leq u \leq 1 + t (see Exercise 25 and Exercise 37 from "Problems on Mathematical Expectation").

Z = I [ 0 , 1 ] ( X ) 4 X + I ( 1 , 2 ] ( X ) ( X + Y ) Z = I_{\left[0 , 1\right]} \left(X\right) 4 X + I_{\left(1 , 2\right]} \left(X\right) \left(X + Y\right)
E [ X ] = 313 220 , E [ Z ] = 5649 1760 , E [ Z 2 ] = 4881 440 E \left[X\right] = \frac{313}{220} , E \left[Z\right] = \frac{5649}{1760} , E \left[Z^{2}\right] = \frac{4881}{440}

Determine Var [Z]Var \left[Z\right] and Cov [X,Z]Cov \left[X , Z\right]. Check with discrete approximation.

Pfeiffer, Applied Probability, 12.4 Problems on Variance, Covariance, Linear Regression, exercise 32

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Adapted from Applied Probability © 2009 Paul E. Pfeiffer. Licensed under CC BY 3.0. Source: Applied Probability. Imported at revision d7a0420.