A farmer has 320 m of fencing to enclose a rectangular field along a straight river. No fence is needed along the river. Find the largest area A that can be enclosed.
Optimization worksheet with answers
A rectangular pen is fenced with 360 m of fencing and divided into two parts by one extra fence parallel to the sides of length x (three fences of length x and two of length y in total). Find the length x that gives the largest total area.
A closed cylindrical can (with a top and a bottom) must hold 250 cm³. The metal used is proportional to the total surface area. Find the smallest possible surface area A.
A closed cylindrical can (with a top and a bottom) must hold 750 cm³. The metal used is proportional to the total surface area. Find the radius r that uses the least material.
A company sells q units per week. The price at which it can sell them is p = 80 − 2q euros per unit, and the cost is C(q) = 200 + 20q euros. Find the price p that maximises profit.
A small firm sells its product at a fixed market price of €25 per unit. Producing q units costs C(q) = 3600 + 8q + 0.01q² euros. Find the maximum profit P.
Answer key
- 1. A = 12800 m²
- 2. x = 60 m
- 3. A = 219.7 cm²
- 4. r = 4.924 cm
- 5. p = 50 €
- 6. P = 3625 €
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