Let Y₁ and Y₂ be discrete random variables with joint probability distribution as shown in the following table: Table 1: Joint mass function for (Y₁, Y₂). У1 Y₂ -1 0 +1 -1 1/16 3/16 1/16 0 3/16 0 3/16 +1 1/16 3/16 1/16 Answer the following: a) Calculate the covariance of Y₁ and Y₂. b) Are Y₁ and Y₂ independent? Are two uncorrelated random variables always independent? Explain.