Question 393801
mean: {{{mu =E(X)= 0*0.47 + 1*0.40 + 2*0.13 = 0.66}}}
variance: {{{sigma^2 = E(X^2) - mu^2 = 0^2*0.47 + 1^2*0.40 + 2^2*0.13 - (0.66)^2 = 0.92 - 0.4356 = 0.4844}}}
==> standard deviation = {{{sigma = sqrt(0.4844) = 0.696}}}, to 3 decimal places.


I hope you finally get it...