Question

The radius of the base of a right circular cylinder is increased by 75% and the height is
decreased by 50%. Find the per cent increase or decrease in the (1) volume, and (ii) curved
surface area.​

Answer 1

Answer:

Curved surface area of cylinder (S

1

)=2πrh

radius is increased by 75%

So,new radius =1.75r

height is decreased by 50% so the

new heights 0.5h

Curved surface area (S

2

)=2π(1.75)r(0.5h)

=1.75πrh

Curved surface area decreases by =(

2πrh

2πrh−1.75πrh

×100)%

=(

2πrh

0.25πrh

×100)%

=12.5%