Question

Determine the mean and variance of the random variable with the following probability mass function f (x) (27/13)(1/3)*, x 1,2,3 Round your answers to three decimal places (e.g. 98.765) Mean- Variance

Answer 1

mean E(X)= $\sum$ xP(x)=1*(27/13)*(1/3)+2*(27/13)*(1/3)²+3*(27/13)*(1/3)³ =1.385

variance = $\sum$ (x-mean)²*P(x)=(1-1.385)²*(27/13)*(1/3)+(2-1.385)²*(27/13)*(1/3)²+(3-1.385)²*(27/13)*(1/3)³ =0.391 ( please try 0.390 if this comes wrong due to rounding)