Quantitative Methods Q182

0. The joint probabilities for X and Y are P(X=10, Y=5) = 0.3, and P(X=20, Y=8) = 0.7. The covariance of XY is closest to:

  • Option : C
  • Explanation : The joint probabilities in the question are given as follows:
    X, Y 5 8
    10 0.3 
    20 0.7
    E(X) = 0.3 (10) + 0.7 (20) = 17
    E(Y) = 0.3 (5) + 0.7 (8) = 7.1
    Cov (XY) = 0.3 (10 - 17) (5 - 7.1) + 0.7 (20 - 17) (8 - 7.1) = 6.3
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