A farmer has 200 m of fencing to enclose a rectangular field along a straight river. No fence is needed along the river. Find the length x of each side perpendicular to the river for the largest area.
Optimization worksheet with answers
A rectangular pen is fenced with 72 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 largest total area A that can be enclosed.
A closed cylindrical can (with a top and a bottom) must hold 500 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 500 cm³. The metal used is proportional to the total surface area. Find the height h of the can that uses the least material.
A small firm sells its product at a fixed market price of €25 per unit. Producing q units costs C(q) = 100 + 16q + 0.1q² euros. Find the maximum profit P.
A theatre sells 1700 tickets per show at €10 each. Market research shows that every €1 increase in the ticket price means 50 fewer tickets sold (and every €1 decrease, 50 more). Find the ticket price p that maximises revenue.
Answer key
- 1. x = 50 m
- 2. A = 216 m²
- 3. A = 348.7 cm²
- 4. h = 8.603 cm
- 5. P = 102.5 €
- 6. p = 22 €
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