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Aptitude · Q31

Mensuration 3d

Competitive Exams · Aptitude · question 31

Q31

The height of a solid cylinder in 30 cm and the diameter of its base is 10 cm. Two identical conical holes each of radius 5 cm and height 12 cm are drilled out. What is the surface area (in cm2) of the remaining solid?

A.
430π
Answer
B.
230π
C.
330π
D.
120π

Answer: Option A

Solution

Answer: Option A
Solution:
Mensuration 3D mcq question image
L.S.A. of cylinder = 2πrh
= 2 × × 5 × 30
= 300π
L.S.A. of cones = 2[πr]
= 2[π × 5 × 13]
= 130π
T.S.A. of remaining part
= 300π + 130π
= 430π