Question

If the radius of cylinder is doubled, but the height is reduced by 50%, the percentage change in volume is
(a) 50%
(b) 75%
(c) 100%
(d) 25%

{AMU +2 ENTRANCE PAPER 2016-17}

Answer 1

Hi Friend ✋✋✋

Let the radius of cylinder be 'r'
and height be 'h'

then volume = πr²h

When radius is doubled and Height is reduced to 50%

then new radius , r' = 2r

New height h' = h/2

then volume = π × (2r)² × h/2

= π × 4r² × h/2

= 2πr²h

So it is doubled and 100% is increased

so your answer is (c)


Hope it helps

Answer 2

Hello DEAR,


LET THE RADIUS OF THE CYLINDER BE - - R--
AND THE HEIGHTS IS - - H--

WE KNOW THAT THE VOLUME OF CYLINDER

= > πr²h,





WHEN THR RADIUS IS DOUBLED AND

HEIGHT IS REDUCED BY 50%


THE NEW RADIUS R=2r


AND THE NEW HEIGHT = H = h/2

THEN THE VOLUME =π×(2r)² ×(h/2)

=>π × 4r² ×h/2

=> 2πr²h

HENCE IT IS DOUBLE

SO, THAT THE 100% IS INCREASED

I HOPE ITS HELP YOU DEAR,

THANKS