2018 · Q93
The surface area of a closed cylindrical box is 352 square cm. If its height is 10 cm, then what is its diameter? (Use π = 22/7)
Elementary MathematicsMensuration
- A4 cm
- B8 cm
- C9.12 cm
- D19.26 cm
Explanation
Total surface area 2πr(h + r) = 352 with h = 10 gives r(10 + r) = 56, i.e. r² + 10r − 56 = 0, so r = 4 cm. The diameter is 8 cm, option (B).