Volume of material used in constructing a hollow cylinder of height 24 cm and thickness 1 cm is 96π cm3. What is the sum of the internal and external radii?

Correct option is C

Let the radii of hollow cylinder are be R and r
Height = h
As per question R – r = 1 cm
As we know
Volume of hollow cylinder = π(R-r)²h
96 π = π(R+r)(R-r)24
96 π = π(R+r)(1)24
96 π = π(R+r)(1)24
R+r = 96/24
R + r = 4