Question

Ram has a conical cap of diameter 14 cm and height 24 cm . If 1 bottle of paint can paint 50 cm2 , then how many bottles are needed to completely paint the cap from outside

Answer 1

First we have to calculate slant height of the cone:

s² = h² + r²

And because the diameter is 14 cm, r = 7 cm.

s² = 24² + 7²

s² = 576 + 49 = 625

s = √625

s = 25 cm

Then we will calculate the lateral surface area:

LSA = s r π = 25 · 7 π = 175 π = 175 · 3.14 = 549.5 cm² ≈ 550 cm²

And if 1 bottle of paint can paint 50 cm² :

550 cm² : 50 cm² = 11

Answer: 11 bottles are needed to completely paint the cap from outside.