Answer:
(1) -0.833
(2) 0.80
(3) 0.70
(4) 390
(5) 90
(7) 48
Step-by-step explanation:
Given:
E (X) = 100, E (Y) = 120, E (Z) = 130
Var (X) = 9, Var (Y) = 16, Var (Z) = 25
Cov (X, Y) = -10, Cov (X, Z) = 12, Cov (Y, Z) = 14
The formulas used for correlation is:

(1)
Compute the value of Corr (X, Y)-

(2)
Compute the value of Corr (X, Z)-

(3)
Compute the value of Corr (Y, Z)-

(4)
Compute the value of E (3X+4Y-3Z)-

(5)
Compute the value of Var (3X-3Z)-
![Var (3X-3Z)=[(3)^{2}\times Var(X)]+[(-3)^{2}\times Var (Z)]+(2\times3\times-3\times Cov(X, Z)]\\=(9\times9)+(9\times25)-(18\times12)\\=90](https://tex.z-dn.net/?f=Var%20%283X-3Z%29%3D%5B%283%29%5E%7B2%7D%5Ctimes%20Var%28X%29%5D%2B%5B%28-3%29%5E%7B2%7D%5Ctimes%20Var%20%28Z%29%5D%2B%282%5Ctimes3%5Ctimes-3%5Ctimes%20Cov%28X%2C%20Z%29%5D%5C%5C%3D%289%5Ctimes9%29%2B%289%5Ctimes25%29-%2818%5Ctimes12%29%5C%5C%3D90)
(6)
Compute the value of Var (3X+4Y-3Z)-
![Var (3X+4Y-3Z)=[(3)^{2}\times Var(X)]+[(4)^{2}\times Var(Y)]+[(-3)^{2}\times Var (Z)]+[(2\times3\times4\times Cov(X, Y)]+[(2\times3\times-3\times Cov(X, Z)]+[(2\times4\times-3\times Cov(Y, Z)]\\=(9\times9)+(16\times16)+(9\times25)+(24\times-10)-(18\times12)-(24\times14)\\=-230](https://tex.z-dn.net/?f=Var%20%283X%2B4Y-3Z%29%3D%5B%283%29%5E%7B2%7D%5Ctimes%20Var%28X%29%5D%2B%5B%284%29%5E%7B2%7D%5Ctimes%20Var%28Y%29%5D%2B%5B%28-3%29%5E%7B2%7D%5Ctimes%20Var%20%28Z%29%5D%2B%5B%282%5Ctimes3%5Ctimes4%5Ctimes%20Cov%28X%2C%20Y%29%5D%2B%5B%282%5Ctimes3%5Ctimes-3%5Ctimes%20Cov%28X%2C%20Z%29%5D%2B%5B%282%5Ctimes4%5Ctimes-3%5Ctimes%20Cov%28Y%2C%20Z%29%5D%5C%5C%3D%289%5Ctimes9%29%2B%2816%5Ctimes16%29%2B%289%5Ctimes25%29%2B%2824%5Ctimes-10%29-%2818%5Ctimes12%29-%2824%5Ctimes14%29%5C%5C%3D-230)
But this is not possible as variance is a square of terms.
(7)
Compute the value of Cov (3X, 2Y+3Z)-
