1. **State the problem:** Simplify the expression $$11 (3\sqrt{0.4} + \sqrt{10}) \sqrt{2.5}$$. 2. **Recall the properties of square roots:** - $\sqrt{a} \times \sqrt{b} = \sqrt{ab}$ - Multiplication is distributive over addition. 3. **Calculate each square root approximately:** - $\sqrt{0.4} \approx 0.6325$ - $\sqrt{10} \approx 3.1623$ - $\sqrt{2.5} \approx 1.5811$ 4. **Evaluate inside the parentheses:** $$3 \times 0.6325 + 3.1623 = 1.8975 + 3.1623 = 5.0598$$ 5. **Multiply by $\sqrt{2.5}$:** $$5.0598 \times 1.5811 \approx 7.999$$ 6. **Multiply by 11:** $$11 \times 7.999 \approx 87.989$$ **Final answer:** $$\boxed{87.99}$$ (rounded to two decimal places)