GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 12 Dec 2019, 12:16

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

To create a part for a certain piece of machinery, four equal-size wed

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Senior RC Moderator
User avatar
V
Joined: 02 Nov 2016
Posts: 4591
GPA: 3.39
To create a part for a certain piece of machinery, four equal-size wed  [#permalink]

Show Tags

New post Updated on: 10 May 2017, 12:16
1
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

83% (01:26) correct 17% (01:15) wrong based on 70 sessions

HideShow timer Statistics

Attachment:
234.jpg
234.jpg [ 8.56 KiB | Viewed 1166 times ]
To create a part for a certain piece of machinery, four equal-size wedgeshaped pieces are cut and removed from a circular piece of metal, as illustrated in the diagram above. If the unshaded portion of the circle represents the material remaining after the pieces are removed, what percentage of the original circle remains?

A. 10
B. 20
C. 25
D. 60
E. 80

_________________

Originally posted by SajjadAhmad on 10 May 2017, 12:13.
Last edited by Bunuel on 10 May 2017, 12:16, edited 1 time in total.
Edited the question.
Intern
Intern
avatar
B
Joined: 29 Apr 2017
Posts: 28
Location: India
Concentration: General Management, Other
WE: Engineering (Computer Software)
Re: To create a part for a certain piece of machinery, four equal-size wed  [#permalink]

Show Tags

New post 10 May 2017, 12:23
1
SajjadAhmad wrote:
Attachment:
234.jpg
To create a part for a certain piece of machinery, four equal-size wedgeshaped pieces are cut and removed from a circular piece of metal, as illustrated in the diagram above. If the unshaded portion of the circle represents the material remaining after the pieces are removed, what percentage of the original circle remains?

A. 10
B. 20
C. 25
D. 60
E. 80



IMO, (E) is the answer.

Angle subtended by the unshaded portion = 90 - 18 = 72 degree
Area of the original circle remaining = Area of the 4 unshaded portions = \(\frac{4 * 72 * pi * r ^ 2}{360}\)
So, percentage of the original circle remaining = \(\frac{4 * 72 * pi * r ^ 2 * 100}{pi * r^2 * 360}\)
= 80


If you like my post, please encourage by giving KUDOS :-D
Intern
Intern
avatar
Joined: 03 May 2017
Posts: 5
Schools: CBS '14 (M)
To create a part for a certain piece of machinery, four equal-size wed  [#permalink]

Show Tags

New post 10 May 2017, 13:13
Degrees in a circle: 360
4 pieces cut 18 deg each = 72 degrees cut.

(Area of a circle is proportional to the angle)

% of area remaining: (360-72)/360 = 4/5 ~ 80%
_________________
Abhijit @ Prepitt
GMAT Math Tutor
MBA, Columbia Business School (Graduated 2014)

GMAT Math Workshops ($90/session) | GMAT Math Private Tutoring ($70/hr)
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2809
Re: To create a part for a certain piece of machinery, four equal-size wed  [#permalink]

Show Tags

New post 15 May 2017, 17:33
1
SajjadAhmad wrote:
Attachment:
234.jpg
To create a part for a certain piece of machinery, four equal-size wedgeshaped pieces are cut and removed from a circular piece of metal, as illustrated in the diagram above. If the unshaded portion of the circle represents the material remaining after the pieces are removed, what percentage of the original circle remains?

A. 10
B. 20
C. 25
D. 60
E. 80


Note that each shaded region corresponds to an 18 degree sector. Since there are four of these sectors, they add up to an 18 x 4 = 72-degree sector. Thus, the remaining material corresponds to a 360 - 72 = 288-degree sector. Since the entire circle has 360 degrees, the remaining material is 288/360 = 8/10 = 80% of the original circle.

Answer: E
_________________

Jeffrey Miller

Head of GMAT Instruction

Jeff@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

GMATH Teacher
User avatar
P
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 935
Re: To create a part for a certain piece of machinery, four equal-size wed  [#permalink]

Show Tags

New post 29 Jan 2019, 06:31
SajjadAhmad wrote:
To create a part for a certain piece of machinery, four equal-size wedgeshaped pieces are cut and removed from a circular piece of metal, as illustrated in the diagram above. If the unshaded portion of the circle represents the material remaining after the pieces are removed, what percentage of the original circle remains?

Image

A. 10
B. 20
C. 25
D. 60
E. 80

\(?\,\,\, = \,\,\,\left[ {\,{{{{360}^ \circ } - \left( {4 \cdot {{18}^ \circ }} \right)} \over {{{360}^ \circ }}}\,} \right] \cdot 100\,\,\left( \% \right)\,\,\,\mathop = \limits^{\left( * \right)} \,\,\,{4 \over 5} \cdot 100\left( \% \right)\,\,\, = \,\,\,80\left( \% \right)\)

\(\left( * \right)\,\,{{{{360}^ \circ } - \left( {4 \cdot {{18}^ \circ }} \right)} \over {{{360}^ \circ }}}\,\, = \,\,1 - {{4 \cdot 18} \over {2 \cdot 18 \cdot 10}}\,\, = \,\,1 - {1 \over 5}\)


We follow the notations and rationale taught in the GMATH method.

Regards,
Fabio.
_________________
Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net
GMAT Club Legend
GMAT Club Legend
User avatar
V
Joined: 12 Sep 2015
Posts: 4145
Location: Canada
Re: To create a part for a certain piece of machinery, four equal-size wed  [#permalink]

Show Tags

New post 29 Jan 2019, 06:45
1
Top Contributor
SajjadAhmad wrote:
Attachment:
234.jpg
To create a part for a certain piece of machinery, four equal-size wedgeshaped pieces are cut and removed from a circular piece of metal, as illustrated in the diagram above. If the unshaded portion of the circle represents the material remaining after the pieces are removed, what percentage of the original circle remains?

A. 10
B. 20
C. 25
D. 60
E. 80


IMPORTANT: the diagrams in GMAT problem solving questions are DRAWN TO SCALE unless stated otherwise.
We can use this fact to solve the question by simply "eyeballing" the diagram.

The question is basically asking us to determine what percent of the circle is NOT shaded.

Well, it's pretty obvious that at least 50% is NOT shaded.
So, we can ELIMINATE A, B and C

We're left with D (60% is NOT shaded) and E (80% is NOT shaded)
I'm pretty confident that the correct answer is MUCH closer to 80% that to 60%, so .....

Answer: E

Cheers,
Brent

RELATED VIDEO FROM MY COURSE

_________________
Test confidently with gmatprepnow.com
Image
GMAT Club Bot
Re: To create a part for a certain piece of machinery, four equal-size wed   [#permalink] 29 Jan 2019, 06:45
Display posts from previous: Sort by

To create a part for a certain piece of machinery, four equal-size wed

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne