Question #d9326

1 Answer
Jul 19, 2017

#3r^(-1)#

Explanation:

Volume = #pi*r^2*h#, where #h# = height, or in this case, #2r#.

Volume = #pi*r^2*2r=2pir^3#

Surface area = #2(pi*r^2)+(h*pi*2*r)#, as #h=2r#, #S.A. = 2pir^2+4pir^2=6pir^2#

#S.A. : V#
#6pir^2:2pir^3#

#(6pir^2)/(2pir^3)=3r^(-1)#