If the height of a cylinder becomes 
of the original height and the radius is doubled, then which of the following will be true?
we know that,
The volume of cylinder having base radius = r
And original height of cylinder = h
Volume of cylinder (v) = π × r2 × h
New height H = 
h and
New radius R = 2r 
(new radius = 2 times of original radius)
New volume of cylinder(V) = π × 4r2 × 
h = πr2h = v
Hence, the volume of new cylinder = the volume of original cylinder.
And the answer is (b).
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