Answer
$μ_X=3.3$
$σ=2.3$
Work Step by Step
$μ_X=Σx.p(x)=1\times0.14375+2\times0.275+3\times0.26875+4\times0.1125+5\times0.08125+6\times0.04375+7\times0.025+8\times0.01875+9\times0.0125+10\times0.0125+20\times0.00625=3.3$
$σ=\sqrt {Σ[x^2.p(x)]-μ_X^2}=\sqrt {[1^2\times0.14375+2^2\times0.275+3^2\times0.26875+4^2\times0.1125+5^2\times0.08125+6^2\times0.04375+7^2\times0.025+8^2\times0.01875+9^2\times0.0125+10^2\times0.0125+20^2\times0.00625]-3.3^2}=2.3$
