First metallic cylindr:- volume =πr²h
It is recasted, right!
Then, the volume is πr²h, but the radius and the height are different. The radius =4cm, right!
Then, volume =π*4*4*h
h= 45.9375cm, right!
C.S.A. = 2πrh = 2*π*4*45.9375
T.S.A. = C.S.A. + 2πr²
1255.57cm² ( for the recasted cylinder).
Hope this will help you.