91Ó°ÊÓ

$$\begin{gathered} \text{Critical ratio =}\frac{\text{p}-\text{c}}{\text{p}-\text{v}} \\ \text{=}\frac{\text{25}-\text{15}}{25-10} \\ \text{=}\frac{\text{10}}{15} \\ \text{= 0.666666666666667} \end{gathered}$$

Probability of demand less than 1 = 0, the quantity (Q) is less than the critical ratio (0.66667)

The probability of demand is less than 2 = 0.2, the quantity (Q) is less than the critical ratio (0.66667)

Probability of demand less than 3 = 0.3 (0.2+0.1), the quantity (Q) is less than critical ratio (0.66667)

Probability of demand less than 4 = 0.4 (0.2+0.1+0.1), the quantity (Q) is less than critical ratio (0.66667)

Probability of demand less than 5 = 0.6 (0.2+0.1+0.1+0.2), the quantity (Q) is less than critical ratio (0.66667)

Probability of demand less than 6 = 0.9 (0.2+0.1+0.1+0.2+0.3), the quantity (Q) is more than critical ratio (0.66667)

Thus, the Optimal order quantity is 5.