UPSC CDS Math Volume and Surface Area Questions

Volume of the cylinder formed when sheet of size 2π×4π is rolled along the side 2π
=π×(

2π

2π

)2×4π=4π2
Volume of the cylinder formed when sheet of size 2π×4π is rolled along the side 4π
=π×(‌‌

4π

2π

)2×2π=8π2
Volume of the cylinder formed when sheet of size π×5π is rolled alongthe side π
=π×(

π

2π

)2×5π
=

5π2

4

=1.25π2
Volume of the cylinder formed when sheet of size π×5π is rolled along the side 5π
=π×(‌‌

5π

2π

)2×π
=‌‌

25π2

4

=6.25π2