Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Mensuration: 3D

Question:

A solid metallic cylinder of base radius 4 cm and height $5\frac{1}{3}$ cm is melted and recast into a sphere. What is the surface area of the sphere, in cm2?

Options:

64 π

96 π

80 π

40 π

Correct Answer:

64 π

Explanation:

We know that,

Volume of sphere = \(\frac{4}{3}\)πR3

Surface area of sphere = 4 πR2

Volume of cylinder = πr2h

Radius of cylinder r = 4 cm

We have,

Height of cylinder h = \(\frac{16}{3}\) cm

Now,

\(\frac{4}{3}\) × πR3 = πr2h

R3 = 4 × 4 × \(\frac{16}{3}\) × \(\frac{3}{4}\)

R = 4 cm

Surface area of sphere = 4π × 42 = 64π cm2