Last visit was: 15 Dec 2024, 02:40 It is currently 15 Dec 2024, 02:40
Home
GMAT
Messages
Tests
Schools
Reviews
Social
Chat
My Profile
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
Back to Forum
Create Topic
555-605 Level|   Geometry|   Probability|      
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 15 Dec 2024
Posts: 97,880
Own Kudos:
685,968
 []
Given Kudos: 88,273
Products:
GMAT Club Tests Forum Quiz
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 97,880
Kudos: 685,968
 []
From the set X = {2, 3, 6, 9, 18, 20}, what is the probability of choo 07 Feb 2022, 03:15
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

25% (medium)

Question Stats:

69% (01:07) correct 31% (01:15) wrong based on 48 sessions

History

Date
Time
Result
Not Attempted Yet
From the set X = {2, 3, 6, 9, 18, 20}, what is the probability of choosing a number such that it constructs a triangle whose other two sides are 7 and 11?

A. 1/2
B. 1/3
C. 1/4
D. 1/5
E. 1/6
ShowHide Answer
Official Answer
B
avatar
ATC93
avatar
Joined: 31 Dec 2019
Last visit: 16 Feb 2022
Posts: 17
Own Kudos:
13
Given Kudos: 7
Posts: 17
Kudos: 13
From the set X = {2, 3, 6, 9, 18, 20}, what is the probability of choo 07 Feb 2022, 03:25
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Had to remember the triangle sides rule as to one side cannot be bigger or smaller than the two sides added or subtract…
This leaves 3/6 options or 1/2 A)

Posted from my mobile device
User avatar
RanonBanerjee
User avatar
Joined: 04 Dec 2020
Last visit: 09 Dec 2024
Posts: 36
Own Kudos:
36
Given Kudos: 153
Concentration: Technology, Strategy
Schools: Fuqua '27 (S)
Schools: Fuqua '27 (S)
Posts: 36
Kudos: 36
From the set X = {2, 3, 6, 9, 18, 20}, what is the probability of choo 07 Feb 2022, 03:31
Kudos
Add Kudos
Bookmarks
Bookmark this Post
The other side must be between 11-7=4, and 11+7=18. That should have 6,9 and 18 from the set.

Therefore probability =3/6=1/2

IMO A

Posted from my mobile device
User avatar
kungfury42
User avatar
Joined: 07 Jan 2022
Last visit: 31 May 2023
Posts: 583
Own Kudos:
466
 []
Given Kudos: 725
Schools: NUS '25 (A)
GMAT 1: 740 Q51 V38
GPA: 4
Products:
My Reviews
Schools: NUS '25 (A)
GMAT 1: 740 Q51 V38
Posts: 583
Kudos: 466
 []
From the set X = {2, 3, 6, 9, 18, 20}, what is the probability of choo 07 Feb 2022, 16:03
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
RanonBanerjee
The other side must be between 11-7=4, and 11+7=18. That should have 6,9 and 18 from the set.

Therefore probability =3/6=1/2

IMO A

Posted from my mobile device

In my opinion, 18 is invalid, and the answer should be 1/3. Here's why:

The sum of any two sides of the triangle must be greater than the third side and the difference of any two sides of the triangle must be smaller than the third side.

Hence, the third side of the triangle must lie between 11-7=4 and 7+11=18, where 4 and 18 are not included.

So the only possible choices are 6 and 9, which makes the probability 2/6 or 1/3. Hence, option B.
avatar
bananaKing
avatar
Joined: 18 Sep 2021
Last visit: 02 Mar 2022
Posts: 2
Own Kudos:
4
 []
Given Kudos: 72
Location: Italy
Posts: 2
Kudos: 4
 []
From the set X = {2, 3, 6, 9, 18, 20}, what is the probability of choo 08 Feb 2022, 05:41
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
IMO it is B:

11+7=18, 11-7=4, but these values are excluded. So we are left with: 6,9-> P=2/6 = 1/3
User avatar
GyanaDash
User avatar
Joined: 29 Jun 2020
Last visit: 03 Nov 2024
Posts: 46
Own Kudos:
9
Given Kudos: 71
Location: India
GPA: 3.29
WE:Project Management (Energy)
Posts: 46
Kudos: 9
From the set X = {2, 3, 6, 9, 18, 20}, what is the probability of choo 10 Feb 2022, 02:54
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
From the set X = {2, 3, 6, 9, 18, 20}, what is the probability of choosing a number such that it constructs a triangle whose other two sides are 7 and 11?

A. 1/2
B. 1/3
C. 1/4
D. 1/5
E. 1/6


Let, the 3 sides of the triangle are 7, 11, and L.
Property: Sum of two sides of a triangle is greater than the third side.

If L is the longest side, then:
L<7+11
or, L<18

If 11 is the longest side, then:
7+L>11
or, L>4

So, from the set given, only 6 and 9 satisfy both conditions. Hence, probability = 2/6 or 1/3.
Moderator:
Bunuel
Math Expert
97879 posts