[" The p.m.f.of a r.v."X" is "],[P(x)={[(2x)/(n(n+1)),x=1,2,.....,n],[0," otherwise "]," then "E(x)=]

The p.m.f. of a r.v. X is P(x)={{:((2x)/(n(n+1))","x=1","2","...","n),(0", otherwise"):} , then Var (X) =

The p.m.f. of a r.v. X is P(x)={{:((1)/(15)","x=1","2","…","15),(0", otherwise"):} , then E (X) =

The p.m.f. of a r.v. X is P(x)={{:((c)/(x^(3))","x=1","2","3),(0", otherwise"):},"then" E (X) =

The p.m.f. of a r.v. X is P(x)={{:((3-x)/(10)","x=-1","0","1","2),(0", otherwise"):} then E (X) =

The p.m.f. of a r.v. X is P(x)={{:(kx^(2)","x=1","2","3","4),(0", otherwise"):} , then E (X) =

The p.m.f. of a r.v. X is P(x)={{:(kx^(2)","x=1","2","3","4),(0", otherwise"):} , then E (X) =

The p.m.f. of a r.v. X is P(x)={{:((1)/(15)","x=1","2","…","15),(0", otherwise"):} , then Var (X) =

If the p.m.f of a d.r.v. X is P(X=x) = {{:((x)/(n(n+1))", for","x = 0,1,2,3,...,n"),(" 0,"," otherwise"):} then E(X) = ……

The p.m.f. of a r.v. X is P(x)={{:(2kx","x=1","2","3),(0", otherwise"):} , then E (X) =

The p.m.f. of a r.v. X is P(x){{:(kx^(2)","x=1","2","3","4),(0", otherwise"):} , then Var (X) =