Which of the Following Formula Is Used to Compute Covariance $\frac { \sum _ { i = 1 } ^ { N } \left( x _ { i } - \mu _ { x } \right) \left( y _ { i } - \mu _ { y } \right) } { N }$

Multiple Choice

Which of the following formula is used to compute covariance between two variables X and Y?

A) cov (X,Y) = $\frac { \sum _ { i = 1 } ^ { N } \left( x _ { i } - \mu _ { x } \right) \left( y _ { i } - \mu _ { y } \right) } { N }$
B) cov (X,Y) = $\frac { \sum _ { i = 1 } ^ { N } \left( x _ { i } - \mu _ { x } \right) ^ { 2 } } { N }$
C) cov (X,Y) = $\sum_{i=1}^{N} \frac{\left(x_{i}-\mu_{x}\right) ^{2}}{y_{i}-\mu_{y}}$

D) cov (X,Y) = $\frac{\sum_{i=1}^{N}\left(x_{i}-\mu_{x}\right) ^{2}}{N^{2}}$