1. **State the problem:** We need to find the number of generating sets $x$ that minimizes the cost function $$c[x] = 0.1x^2 - 0.7x + 2.425$$ where $c[x]$ is the cost in hundreds of naira. 2. **Recall the formula:** For a quadratic function $$c[x] = ax^2 + bx + c,$$ the minimum (if $a > 0$) occurs at $$x = -\frac{b}{2a}.$$ Here, $a = 0.1$ and $b = -0.7$. 3. **Calculate the vertex:** $$x = -\frac{-0.7}{2 \times 0.1} = \frac{0.7}{0.2} = 3.5.$$ 4. **Interpretation:** Since $x$ represents the number of generating sets, the company should manufacture approximately 3 or 4 units to minimize cost. 5. **Final answer:** The cost is minimized when $x = 3.5$ generating sets, so practically either 3 or 4 units should be produced to minimize cost.