Suppose$$X$$B$($n$,$p$).$ Then the expectation$/$mean of X is $[$ Select $]["$np$(1-$ p$)","$n$","$p$","$np$"],$ and the variance of$$X is $[$ Select $]["$np$","$np$(1-$ p$)/2","$p$(1-$ p$)","$np$(1-$ p$)"]$