Chapter 3 - Section 3-4 - Mean and Variance of a Discrete Random Variable - Exercises - Page 77: 3-61

μ=2.8, σ²=1.36

$μ=E(x)=∑xP(x)=0 \times \frac{1}{25}+1 \times \frac{3}{25}+2 \times \frac{5}{25}+3 \times \frac{7}{25}+4 \times \frac{9}{25}=\frac{70}{25}=2.8$ $σ²=V(x)=∑x²P(x)−μ²=0^{2} \times \frac{1}{25}+1^{2} \times \frac{3}{25}+2^{2} \times \frac{5}{25}+3^{2} \times \frac{7}{25}+4^{2} \times \frac{9}{25}-2.8^{2}=1.36$