NEW HERE? LEARN MORE
closeclose
Last visit was: 26 Apr 2024, 11:30 It is currently 26 Apr 2024, 11:30
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

Two polygons A and B have number of sides as a and b respectively, wha

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92948
Own Kudos [?]: 619220 [3]
Given Kudos: 81609
Send PM
CAT Tests Forum Quiz Mode
Two polygons A and B have number of sides as a and b respectively, wha [#permalink] New post   06 May 2020, 22:39
3
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

35% (medium)

Question Stats:

71% (01:26) correct 29% (01:23) wrong based on 95 sessions
Hide Show timer Statistics
Two regular polygons A and B have number of sides as a and b respectively, what is the value of |a − b|?

(1) Sum of interior angles of polygon A is 360 degree greater than that of polygon B.
(2) The number of diagonals of polygon A is 20.
 
ShowHide Answer
Official Answer
A
User avatar
L
GMATinsight
GMAT Club Legend
GMAT Club Legend
Joined: 08 Jul 2010
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Posts: 5962
Own Kudos [?]: 13391 [2]
Given Kudos: 124
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Send PM
Reviews Badge
Re: Two polygons A and B have number of sides as a and b respectively, wha [#permalink] New post   Updated on: 07 May 2020, 06:36
2
Kudos
Expert Reply
Bunuel wrote:
Two polygons A and B have number of sides as a and b respectively, what is the value of |a − b|?

(1) Sum of interior angles of polygon A is 360 degree greater than that of polygon B.
(2) The number of diagonals of polygon A is 18.

Project PS Butler


Subscribe to get Daily Email - Click Here | Subscribe via RSS - RSS


Question: |a − b|=?

Statement 1: Sum of interior angles of polygon A is 360 degree greater than that of polygon B.

CONCEPT: Sum of Interior angles of an \(n\) sided polygon \(= 180*(n-2)\)


i.e. 180*(a-2) = 180*(b-2) + 380

i.e. (a-2) = (b-2) + 2

i.w. a = b+2

i.e. a-b = 2

i.e. la-bl = 2

SUFFICIENT

Statement 2: The number of diagonals of polygon A is 18.

CONCEPT: Number of diagonals in an \(n\) sided polygon \(= nC_2 - n = \frac{n*(n-3)}{2}\)


i.e. a(a-3)/2 = 20
i.e. a(a-3) = 40
i.e. a = 8

But No information about b hence

NOT SUFFICIENT

Answer: Option A

Originally posted by GMATinsight on 06 May 2020, 23:07.
Last edited by GMATinsight on 07 May 2020, 06:36, edited 1 time in total.
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92948
Own Kudos [?]: 619220 [0]
Given Kudos: 81609
Send PM
CAT Tests Forum Quiz Mode
Re: Two polygons A and B have number of sides as a and b respectively, wha [#permalink] New post   07 May 2020, 03:03
Expert Reply
GMATinsight wrote:
Bunuel wrote:
Two polygons A and B have number of sides as a and b respectively, what is the value of |a − b|?

(1) Sum of interior angles of polygon A is 360 degree greater than that of polygon B.
(2) The number of diagonals of polygon A is 18.

Project PS Butler


Subscribe to get Daily Email - Click Here | Subscribe via RSS - RSS


Question: |a − b|=?

Statement 1: Sum of interior angles of polygon A is 360 degree greater than that of polygon B.

CONCEPT: Sum of Interior angles of an \(n\) sided polygon \(= 180*(n-2)\)


i.e. 180*(a-2) = 180*(b-2) + 380

i.e. (a-2) = (b-2) + 2

i.w. a = b+2

i.e. a-b = 2

i.e. la-bl = 2

SUFFICIENT

Statement 2: The number of diagonals of polygon A is 18.

CONCEPT: Number of diagonals in an \(n\) sided polygon \(= nC_2 - n = \frac{n*(n-3)}{2}\)


i.e. a(a-3)/2 = 18
i.e. a(a-3) = 36

NOT POSSIBLE

No information about b hence

NOT SUFFICIENT

Answer: Option A

Bunuel: There is some problem with statement 2 number 18. No polygon has 18 diagonals

________________
Thank you. Fixed.
User avatar
L
GMATWhizTeam
GMATWhiz Representative
Joined: 07 May 2019
Posts: 3409
Own Kudos [?]: 1800 [1]
Given Kudos: 68
Location: India
GMAT 1: 740 Q50 V41
GMAT 2: 760 Q51 V40
Send PM
Re: Two polygons A and B have number of sides as a and b respectively, wha [#permalink] New post   07 May 2020, 04:24
1
Kudos
Expert Reply
Bunuel wrote:
Two regular polygons A and B have number of sides as a and b respectively, what is the value of |a − b|?

(1) Sum of interior angles of polygon A is 360 degree greater than that of polygon B.
(2) The number of diagonals of polygon A is 20.



Solution


Step 1: Analyse Question Stem


    • Regular polygon A has “a” number of sides.
    • Regular polygon B has “b” number of sides.
    • We need to find the value of |a – b|
      o i.e. we need to find the positive difference between a and b.

Step 2: Analyse Statements Independently (And eliminate options) – AD/BCE


Statement 1: Sum of interior angles of polygon A is 360 degree greater than that of polygon B.

    • We know that the sum of interior angles of a regular polygon \(= (n- 2)*180 \) degrees, where n is the number of sides.
    • Now, According to this statement:\( (a – 2)*180 – (b-2)*180 = 360 \)degrees
      o \(⟹ a – 2 – b+ 2 = 2 ⟹ a – b = 2\)
Hence, statement 1 is sufficient and we can eliminate answer Options B, C and E.

Statement 2: The number of diagonals of polygon A is 20.

    • This statement gives no information about polygon B.
    • So, we cannot find |a – b| from this statement.
Hence, statement 2 is NOT sufficient.
Thus, the correct answer is Option A.
User avatar
G
sambitspm
Senior Manager
Senior Manager
Joined: 05 Aug 2019
Posts: 317
Own Kudos [?]: 279 [1]
Given Kudos: 130
Location: India
Concentration: Leadership, Technology
GMAT 1: 600 Q50 V22
GMAT 2: 670 Q50 V28 (Online)
GPA: 4
Send PM
Re: Two polygons A and B have number of sides as a and b respectively, wha [#permalink] New post   07 May 2020, 08:37
1
Kudos
Two regular polygons A and B have number of sides as a and b respectively, what is the value of |a − b|?

(1) Sum of interior angles of polygon A is 360 degree greater than that of polygon B.
(2) The number of diagonals of polygon A is 20.

Solution
STATEMENT A:
Say Polygon A has m sides, and Polygon B has n sides.
So sum of interior angles is (2n-2)90

(2m-2 - 2n+2) * 90 = 360
SUFFICIENT

STATEMENT B:
Number of diagonals of Polygon A is given.
Number of diagonals in a polygon is n(n-3)/2
But no information about Polygon B is given, hence INSUFFICIENT


ANSWER - A
avatar
G
poojakhanduja3017
Manager
Manager
Joined: 02 Dec 2018
Posts: 124
Own Kudos [?]: 100 [1]
Given Kudos: 36
Location: India
Schools: Goizueta '22 Wharton '22 IIMA PGPX "21 ISB '21 INSEAD Jan '20 LBS '22 Stanford '22 NUS '22 Booth '22 Cass '21
GMAT 1: 690 Q50 V32
GPA: 3.98
Send PM
Reviews Badge
Re: Two polygons A and B have number of sides as a and b respectively, wha [#permalink] New post   07 May 2020, 15:13
1
Kudos
Very easy question. The answer is A
Statement 1: Sum of interior angles of polygon A is 360 degree greater than that of polygon B.

CONCEPT: Sum of Interior angles of an n-sided polygon =180*(n−2)=180*(n−2)

Step 1: 180*(a-2) = 180*(b-2) + 360
Step 2: (a-2) = (b-2) + 2
Step 3: a = b+2
Step 4: a-b = 2
Answer : la-bl = 2

SUFFICIENT

Statement 2: The number of diagonals of polygon A is 18.
We know nothing about B, hence NOT SUFFICIENT.
GMAT Club Bot
gmatclubot
Re: Two polygons A and B have number of sides as a and b respectively, wha [#permalink]
07 May 2020, 15:13
Moderator:
Bunuel
Math Expert
92947 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions