In a cylinder, if radius is doubled and height is halved, curved surface area will be (a) halved      (b)  doubled       (c)  same      (d)   four times

Explanation

As we know that C.S.A of cylinder is `2pirh`

C.S.A of cylinder = `2xxpixx2rxxh/2` (`therefore` radius=`2r` and height=`h/2`)

C.S.A of cylinder=`2pirh`

So, C.S.A remains the same.

Hence, option(c) is correct.