Question 1184331
X  = 6 8 12 14 18
P(X)  = 0.09 0.11 0.09 0.08 0.63


===> {{{E(X) = mu = sum(x*p(x))=6*0.09+8*0.11+12*0.09+14*0.08+18*0.63 = 374/25 }}}


===>  {{{sigma^2 = E(X^2) - mu^2 = 6^2*0.09+8^2*0.11+12^2*0.09+14^2*0.08+18^2*0.63 = 6076/25 - (374/25)^2 = 12024/625 = 19.2384}}}


===> {{{sigma = (6*sqrt(334))/25 = 4.3862}}}, to 4 d.p.