For a random vector \b{X} = X_1,X_2,X_3,X_4

I am given only \bar{\b{X}} a 4x1 matrix and \b{S} a 4x4 matrix.

I am asked to find the total mean and variance for \b{X}

I know for the variance I need to find |\b{S}| but how do I find the total mean?