An open box is made from a rectangular sheet of cardboard 10 cm × 16 cm by cutting equal squares of side x from the four corners and folding up the sides. Find the largest possible volume V.
Optimization worksheet with answers
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.
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 height h of the can that uses the least material.
An open box (no lid) with a square base must hold 108000 cm³. Use the least possible material, that is the smallest area of the base plus the four sides. Find the minimum surface area S.
A small firm sells its product at a fixed market price of €25 per unit. Producing q units costs C(q) = 100 + 4q + 0.5q² euros. Find the output q that maximises profit.
A company sells q units per week. The price at which it can sell them is p = 90 − 0.2q euros per unit, and the cost is C(q) = 600 + 55q euros. Find the weekly output q that maximises profit.
Answer key
- 1. V = 144 cm³
- 2. A = 12800 m²
- 3. h = 9.847 cm
- 4. S = 10800 cm²
- 5. q = 21 units
- 6. q = 87.5 units
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