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

It is currently 15 Oct 2019, 04:16

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

The data in the table show cell phone ownership status by grade level

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

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58327
The data in the table show cell phone ownership status by grade level  [#permalink]

Show Tags

New post 23 Mar 2018, 00:00
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

27% (01:37) correct 73% (01:26) wrong based on 63 sessions

HideShow timer Statistics

The data in the table show cell phone ownership status by grade level of 300 middle school students. If one of the 300 students is randomly selected, what is the probability that the student owns a cell phone, given that the student is a seventh grader?

Image


A. 11/60

B. 11/100

C. 163/300

D. 55/163

E. 11/20


Attachment:
2018-03-23_1057.png
2018-03-23_1057.png [ 46.14 KiB | Viewed 970 times ]

_________________
Current Student
User avatar
P
Joined: 07 Jan 2016
Posts: 1088
Location: India
GMAT 1: 710 Q49 V36
Reviews Badge
Re: The data in the table show cell phone ownership status by grade level  [#permalink]

Show Tags

New post 23 Mar 2018, 00:17
Bunuel wrote:
The data in the table show cell phone ownership status by grade level of 300 middle school students. If one of the 300 students is randomly selected, what is the probability that the student owns a cell phone, given that the student is a seventh grader?

Image


A. 11/60

B. 11/100

C. 163/300

D. 55/163

E. 11/20


Attachment:
2018-03-23_1057.png



total students 300

7th grader with cellphone 55

prob = 55/300 = 11/60
Manager
Manager
User avatar
B
Joined: 28 Jan 2018
Posts: 50
Location: Netherlands
Concentration: Finance
GMAT 1: 710 Q50 V36
GPA: 3
Re: The data in the table show cell phone ownership status by grade level  [#permalink]

Show Tags

New post 23 Mar 2018, 10:21
Bunuel wrote:
The data in the table show cell phone ownership status by grade level of 300 middle school students. If one of the 300 students is randomly selected, what is the probability that the student owns a cell phone, given that the student is a seventh grader?

Image


A. 11/60

B. 11/100

C. 163/300

D. 55/163

E. 11/20


Attachment:
2018-03-23_1057.png


The probability that the random selected student will be a 7th grader and own a cell phone will be: \(\frac{55}{300} = \frac{11}{60}\) (A)
Intern
Intern
avatar
B
Joined: 26 Jun 2014
Posts: 20
Re: The data in the table show cell phone ownership status by grade level  [#permalink]

Show Tags

New post 23 Mar 2018, 13:15
Bunuel wrote:
The data in the table show cell phone ownership status by grade level of 300 middle school students. If one of the 300 students is randomly selected, what is the probability that the student owns a cell phone, given that the student is a seventh grader?

Image


A. 11/60

B. 11/100

C. 163/300

D. 55/163

E. 11/20



The question says "GIVEN that the student is in the 7th grade". That means we can ignore the rest of the chart and only look at the 7th grade row. 55/100 is 11/20, answer E.
Manager
Manager
User avatar
B
Joined: 28 Jan 2018
Posts: 50
Location: Netherlands
Concentration: Finance
GMAT 1: 710 Q50 V36
GPA: 3
Re: The data in the table show cell phone ownership status by grade level  [#permalink]

Show Tags

New post 23 Mar 2018, 14:09
Chakolate wrote:
Bunuel wrote:
The data in the table show cell phone ownership status by grade level of 300 middle school students. If one of the 300 students is randomly selected, what is the probability that the student owns a cell phone, given that the student is a seventh grader?

Image


A. 11/60

B. 11/100

C. 163/300

D. 55/163

E. 11/20



The question says "GIVEN that the student is in the 7th grade". That means we can ignore the rest of the chart and only look at the 7th grade row. 55/100 is 11/20, answer E.


We're asked to choose 1 student from the total of 300, so your answer is wrong!
Intern
Intern
avatar
B
Joined: 26 Jun 2014
Posts: 20
Re: The data in the table show cell phone ownership status by grade level  [#permalink]

Show Tags

New post 23 Mar 2018, 19:23
hoang221 wrote:

We're asked to choose 1 student from the total of 300, so your answer is wrong!


You say I'm wrong, I say you're wrong. I guess we'll have to wait until Bunuel weighs in.
Intern
Intern
avatar
B
Joined: 15 Feb 2019
Posts: 4
GMAT 1: 690 Q49 V34
GMAT 2: 690 Q47 V38
GMAT 3: 710 Q50 V36
The data in the table show cell phone ownership status by grade level  [#permalink]

Show Tags

New post 07 Jul 2019, 08:38
Use Bayes' theorem. P(A|B) = P(B|A)P(A)/P(B). We have:

P(A|B) is the prob that given a student in 7th grade, he/she has a smartphone (what we want to find).

P(B|A) is the prob. that given a student in 7th grade with a smartphone, he/she is in the 7th grade. Therefore, P(B|A) = 1.

P(A) is the prob. that a 7th grade student has a smartphone. Hence, P(A) = 55/300.

P(B) is the prob. that a student is in 7th grade. Thus, P(B) = 1/3.

Finally, P(A|B) = 1(55/300)/3 = 165/300 = 11/20.

Hope this helps.
GMAT Club Bot
The data in the table show cell phone ownership status by grade level   [#permalink] 07 Jul 2019, 08:38
Display posts from previous: Sort by

The data in the table show cell phone ownership status by grade level

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





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