The curved surface area of a cylinder is 24/7 times the total flat surface area(top +bottom).If the biggest possible cone is cut out from the cylinder, what is the ratio of the curved surface area of the cone to its flat surface area?
A) 24/7
B) 25/7
C) 27/7
D) 29/7
E) 30/7
(Asked by Vivek)
i think its b
plz explain what is flat surface area
Dear Harleen,
Coloured portion in above diagram is flat surfave area of the cylinder.
B)
hmmmm its A)..
AAAAAAAAAA
any1 with method ?
curved surface ar of cyl = 24/7 * (total flat surface area)
2 Pi r h = 24/7 (2 Pi r^2)
this gives h = 24/7 * r
slat height of cone l = [ h^2 + r^2 ] ^ (1/2)
curved surface area (CSA) of cone = pi * r * l
flat surface area (FSA) of cone = pi * r * r
ratio CSA/FSA = l/r
= { [ h^2 + r^2 ] ^ (1/2) } / r
substituting h = 24/7 * r
gives the ratio = 25/7
hhm difficult one.
thanks Viren for your herculean effort !!!
dont think such qs will be asked in gre!
B
thts the only method i can think of too..but its lengthy, not the GRE type…any alternative suggestion plz?