Rectangular label wrapped around cylinder

IMO C.
Here is how I approached.

The length of the strip is 21.5 cm. Imagine that it is rolled into a cylinder with some part of the strip overlapping. The overlapping part should not be concerned for finding the volume.

We know that volume of cylinder is Pi*r^2 * height.

Stmt 1 tells us to ignore 0.5 cms of the length.
so circumferance of the cylinder = 21cms.
from that we can find r
ie 2*Pi*r = 21.
= 2* 22/7 * r = 21.
So r = (21 *7) /(2 *22) -(1)

So stmt 1 gives us a value of r. ( No need to calculate the value coz this is a DS problem).

But still insufficient coz we dont know the width of the strip , which is the height of the cylinder.

so insufficient.


Stmt 2. this gives us width of the strip , which is height h.

but no r. Hence not sufficient.

Considering them together, we get both r and h. So can find the volume.

So C.


(my perspective: this is a relatively easy problem, in the 400 -500 range.)


Ht Helps
-V

Thank you, vittalgmat. Could you please tell me what part of the question stands for "width of the strip == height of cylinder" ? Is it "exactly covers the curved surface" ?

Imagine a rectangular strip 21 cms long . If u roll hte strip along the long side, the longer side form a circle.

From the problem "the shorter ends overlapping" refers to the width.
Also "exactly covers the curved surface" means that width of the strip == height of cylinder.

Ht helps