Question

18. The radius of a cylinder is increased by 50% and its height is de-
creased by 40%. The percentage change in its volume is :
एक वेलन की त्रिज्या 50% बढ़ाया जाता है तथा ऊंचाई को 40% घटाया जाता है। इसके
आयतन में परिवर्तन प्रतिशत में है :
(2) 25
(3) 35
(4) 45
(1) 15​

Answer 1

let the radius of given cylinder=100cm and it's height is also 100cm.

therefore,

volume= πr^2h

=π × (100cm)^2 ×100cm

= 1000000π cm^3

New radius=(100+50)cm=150cm

New height= (100-40)= 60cm

therefore,

New volume= πr^2h

= π ×(150cm)^2 × 60cm

=1350000π cm^3

Now,

Increase in volume=(1350000π-1000000π)cm^3

=350000π cm^3

Increase%=350000πcm^3÷1000000πcm^3×100%

= 35% ans.