Last visit was: 11 May 2026, 04:54 It is currently 11 May 2026, 04:54
Home
Messages
Tests
Schools
Events
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
User avatar
reply2spg
User avatar
Joined: 12 Oct 2008
Last visit: 05 Oct 2010
Posts: 270
Own Kudos:
4,623
Given Kudos: 2
Posts: 270
Kudos: 4,623
In a certain class, one student is to be selected at random 19 Sep 2009, 14:38
Kudos
Add Kudos
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

35% (medium)

Question Stats:

70% (00:21) correct 30% (00:47) wrong based on 10 sessions

History

Date
Time
Result
Not Attempted Yet
In a certain class, one student is to be selected at random to read. What is the probability that a boy will read?

(1) Two-thirds of the students in the class are boys.
(2) Ten of the students in the class are girls.

Official Guide 12 Question

GMAT Official Guide 12

Question: 3
Page: 273
Difficulty: 600

Find All Official Guide Questions

Video Explanations:



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Data Sufficiency (DS) Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
ShowHide Answer
Official Answer
A
User avatar
maliyeci
User avatar
Joined: 23 Jun 2009
Last visit: 04 Nov 2016
Posts: 200
Own Kudos:
250
Given Kudos: 80
Location: Turkey
Concentration: Finance and Accounting
Schools:UPenn, UMich, HKS, UCB, Chicago
GMAT 2: 740 Q49 V41
Posts: 200
Kudos: 250
In a certain class, one student is to be selected at random 19 Sep 2009, 14:43
Kudos
Add Kudos
Bookmarks
Bookmark this Post
reply2spg
In a certain class, one student is to be selected at random to read. what is the probability that a boy will read?

1. Two-thirds of the students in the class are boys.
2. Ten of the students in the class are girls.

Please explain

Show Spoiler
OA A IMO D
Show more
A
1)suff.
since 2/3 of the students are boys, the prob of that a boy selected is 2/3.
2)insuff.
We know the number of girls. But we do not know the number of boys.
Let the number of boys is 20 then the answer will be 2/3.
And let the number of boys is 30 then the answer will be 3/4.
User avatar
reply2spg
User avatar
Joined: 12 Oct 2008
Last visit: 05 Oct 2010
Posts: 270
Own Kudos:
4,623
Given Kudos: 2
Posts: 270
Kudos: 4,623
In a certain class, one student is to be selected at random 19 Sep 2009, 15:05
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Can you explain 1 in detail?

maliyeci
reply2spg
In a certain class, one student is to be selected at random to read. what is the probability that a boy will read?

1. Two-thirds of the students in the class are boys.
2. Ten of the students in the class are girls.

Please explain

Show Spoiler
OA A IMO D
A
1)suff.
since 2/3 of the students are boys, the prob of that a boy selected is 2/3.
2)insuff.
We know the number of girls. But we do not know the number of boys.
Let the number of boys is 20 then the answer will be 2/3.
And let the number of boys is 30 then the answer will be 3/4.
Show more
User avatar
maliyeci
User avatar
Joined: 23 Jun 2009
Last visit: 04 Nov 2016
Posts: 200
Own Kudos:
250
Given Kudos: 80
Location: Turkey
Concentration: Finance and Accounting
Schools:UPenn, UMich, HKS, UCB, Chicago
GMAT 2: 740 Q49 V41
Posts: 200
Kudos: 250
In a certain class, one student is to be selected at random 20 Sep 2009, 08:20
Kudos
Add Kudos
Bookmarks
Bookmark this Post
it says 2/3 of the students are boy. This can be 20 boys and 10 girls, 30 boys 15 girls or any value that satisfies this 2/3 ratio.

Question asks the probability that a student selected is boy.

if there are 20 boys and 10 girls. Probability will be 20/(20+10)=2/3
User avatar
abhi758
User avatar
Joined: 16 Jul 2009
Last visit: 05 Oct 2016
Posts: 137
Own Kudos:
2,981
Given Kudos: 3
Posts: 137
Kudos: 2,981
In a certain class, one student is to be selected at random 21 Sep 2009, 23:24
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Agree with A.. As you are already provided with the probability fraction in st1, whereas st2 just provides you the information about the no. of girls in the class..



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Data Sufficiency (DS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
Moderators:
Bunuel
Math Expert
110262 posts
GMATBusters
GMAT Tutor
1922 posts