Multiple choice

A bucket is in the shape of the frustum of a right circular cone, whose radii are 5 and 10 mm. The curved surface area is $210$ mm. Find the slant height. (Use $\pi$ = $3$)

  1. $1.76$ mm
  2. $2.6$ mm
  3. $3.5$ mm
  4. $4.66$ mm
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The curved surface area of a frustum is pi * (r1 + r2) * l. Given pi=3, r1=5, r2=10, and area=210, we have 3 * (5 + 10) * l = 210, which simplifies to 45 * l = 210. Solving for l gives 210/45 = 4.66.

AI explanation

Using the curved surface area formula for a frustum, CSA = pi * (R + r) * l, substitute the area as 210, pi = 3, the larger radius R = 10, and the smaller radius r = 5. This gives the equation 210 = 3 * (10 + 5) * l, which simplifies to 210 = 45l. Divide 210 by 45 to find the slant height l = 4.66 mm.

Keep practicing — related questions