Question 1022932
Mean = E(X) = 1*0.27+2*0.31+3*0.18+4*0.09+5*0.15 = 2.54.

Standard deviation = {{{sqrt(Var(X)) = sqrt(E(X^2) - (E(X))^2)}}}

= {{{sqrt( 1^2*0.27+2^2*0.31+3^2*0.18+4^2*0.09+5^2*0.15 - 2.54^2)}}}

={{{sqrt(8.32 - 6.4516) = sqrt(1.8684) = 1.367}}}, to three decimal places.