It is currently 10 Dec 2018, 13:56

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# 30% of the surface area of a right circular cylinder is shad

Author Message
TAGS:
Moderator
Joined: 18 Apr 2015
Posts: 5126
Followers: 76

Kudos [?]: 1028 [0], given: 4631

30% of the surface area of a right circular cylinder is shad [#permalink]  22 Apr 2018, 09:20
Expert's post
00:00

Question Stats:

100% (00:00) correct 0% (00:00) wrong based on 1 sessions
30% of the surface area of a right circular cylinder is shaded. If the diameter of the base of the cylinder is 10 and the height is 4, what is the surface area of the unshaded region?

A. $$27\pi$$

B. $$40\pi$$

C. $$63\pi$$

D. $$70\pi$$

E. $$90\pi$$
[Reveal] Spoiler: OA

_________________
Director
Joined: 07 Jan 2018
Posts: 553
Followers: 4

Kudos [?]: 477 [0], given: 84

Re: 30% of the surface area of a right circular cylinder is shad [#permalink]  24 Apr 2018, 01:29
knowing the formulas for volumes and surface area of solid figure is useful
surface area of a cylinder = 2pi*r(r+h)
since diameter $$= 10$$; $$r = 5$$

Find the total surface are of the cylinder $$= 2*pi*5(5+4) = 90pi$$
$$30$$% of $$90pi$$ $$= 27pi$$ which is the shaded area hence
unshaded area $$= 90pi-27pi = 63pi$$
option c
_________________

This is my response to the question and may be incorrect. Feel free to rectify any mistakes

Last edited by amorphous on 24 Apr 2018, 01:42, edited 2 times in total.
Edited by Carcass
Moderator
Joined: 18 Apr 2015
Posts: 5126
Followers: 76

Kudos [?]: 1028 [1] , given: 4631

Re: 30% of the surface area of a right circular cylinder is shad [#permalink]  24 Apr 2018, 01:43
1
KUDOS
Expert's post
if you use $$\pi$$ copying and paste it from the web, then when you wrap it up with $$tag m$$ the result are strange symbols.

Instead, just write simply \pi and wrap with $$tag m$$

the result is this $$\pi$$

_________________
Re: 30% of the surface area of a right circular cylinder is shad   [#permalink] 24 Apr 2018, 01:43
Display posts from previous: Sort by