Multiple choice

A hollow cylinder having external radius $8$ cm and height $10$ cm has total surface area of $338$ $\pi cm^2$. Find the thickness of the hollow metallic cylinder.

  1. $2$ cm 
  2. $3$ cm
  3. $4$ cm
  4. $5$ cm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total surface area of hollow cylinder = 2 * pi * (R+r) * (R-r+h) = 338 * pi. Given R=8, h=10. 2 * (8+r) * (8-r+10) = 338. (8+r)(18-r) = 169. 144 - 8r + 18r - r^2 = 169. r^2 - 10r + 25 = 0. (r-5)^2 = 0, r=5. Thickness = R - r = 8 - 5 = 3.

Keep practicing — related questions