The Aam-Aadmi Party

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Aman verma: Master | Next Rank: 500 Posts; Posts: 304; Joined: Wed Jan 27, 2010 8:35 amFollowed by: 3 members; Location: International Space Station; Thanked: 11 times

by Aman verma » Sat Nov 30, 2013 5:36 am

Q:In the upcoming Delhi Elections only two major parties are fighting the elections-The Aam-Aadmi Party headed by Arvind kejriwal and The Aam-Aurat party headed by Dr. Sanjay HarshaVardan. 45% of the population support the Aam-Aadmi Party and 30% of the population support The Aam-Aurat Party and 20% of the population support both the parties. One citizen is selected at random from the population named Aman Verma. Find the probability that he supports the Aam-Admi party if it is known that he supports the Aam-Aurat Party. [Edited: Missing information inserted at the end of the third line]

(A)1/3

(B)2/3

(C)5/6

(D)4/7

(E)5/9

Last edited by Aman verma on Sat Nov 30, 2013 9:05 am, edited 1 time in total.

800. Arjun's-Bird-Eye

Source: Beat The GMAT — Problem Solving | Sat Nov 30, 2013 5:36 am

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Sat Nov 30, 2013 8:09 am

Aman verma wrote:Q:In the upcoming Delhi Elections only two major parties are fighting the elections-The Aam-Aadmi Party headed by Arvind kejriwal and The Aam-Aurat party headed by Dr. Sanjay HarshaVardan. 45% of the population support the Aam-Aadmi Party and 30% of the population support The Aam-Aurat Party. One citizen is selected at random from the population named Aman Verma. Find the probability that he supports the Aam-Admi party if it is known that he supports the Aam-Aurat Party.

(A)1/3
(B)2/3
(C)5/6
(D)4/7
(E)5/9

Hi Aman,

As it stands, there is not enough information to answer this question.

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Aman verma: Master | Next Rank: 500 Posts; Posts: 304; Joined: Wed Jan 27, 2010 8:35 amFollowed by: 3 members; Location: International Space Station; Thanked: 11 times

by Aman verma » Sat Nov 30, 2013 9:09 am

Brent@GMATPrepNow wrote:
Hi Aman,

As it stands, there is not enough information to answer this question.

Cheers,
Brent

Hi Brent,

Yes, there was an information missing at the end of the third line, which I have inserted in the original post.I was unable to highlight the missing part as I don't know how to do that. Regret the error.

800. Arjun's-Bird-Eye

aalradadi: Junior | Next Rank: 30 Posts; Posts: 15; Joined: Mon May 06, 2013 11:46 pm

by aalradadi » Sat Nov 30, 2013 9:48 am

What was the answer? And did they wrote an explanation ?

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

The Aam-Aadmi Party

by Brent@GMATPrepNow » Sat Nov 30, 2013 10:03 am

Aman verma wrote:Q:In the upcoming Delhi Elections only two major parties are fighting the elections-The Aam-Aadmi Party headed by Arvind kejriwal and The Aam-Aurat party headed by Dr. Sanjay HarshaVardan. 45% of the population support the Aam-Aadmi Party and 30% of the population support The Aam-Aurat Party and 20% of the population support both the parties. One citizen is selected at random from the population named Aman Verma. Find the probability that he supports the Aam-Admi party if it is known that he supports the Aam-Aurat Party.

(A)1/3
(B)2/3
(C)5/6
(D)4/7
(E)5/9

We can solve this question using the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it.
Here, we have a population of voters, and the two characteristics are:
- pro Aam-Aadmi or not pro Aam-Aadmi
- pro Aam-Aurat or not pro Aam-Aurat

To learn more about this technique, watch our free video: https://www.gmatprepnow.com/module/gmat- ... ems?id=919

Since the question does not ask us to find specific numbers of voters, we can assign a "nice" value to the entire population. Let's say that there are 100 voters altogether.

So, we can set up our diagram as follows:

45% of the population support the Aam-Aadmi Party and 30% of the population support The Aam-Aurat Party
We can add this information to our diagram.

20% of the population support both the parties
We'll add that information as well.

At this point, we can determine the number of voters in each box.

Find the probability that he supports the Aam-Aadmi party if it is known that he supports the Aam-Aurat Party.

So, Aman verma is one of the 30 Aam-Aurat supporters.
Of the 30 Aam-Aurat supporters, 20 also support Aam-Aadmi
So, the required probability = [spoiler]20/30 = 2/3 = B[/spoiler]

---------------------------------------------

Here are some additional practice questions that can be solved using the Double Matrix Method:
- https://www.beatthegmat.com/mba/2011/05 ... question-1
- https://www.beatthegmat.com/mba/2011/05 ... question-2
- https://www.beatthegmat.com/mba/2011/05 ... question-3
- https://www.beatthegmat.com/ds-quest-t187706.html
- https://www.beatthegmat.com/overlapping ... 83320.html
- https://www.beatthegmat.com/finance-maj ... 67425.html
- https://www.beatthegmat.com/ds-french-j ... 22297.html
- https://www.beatthegmat.com/sets-t269449.html#692540
- https://www.beatthegmat.com/in-costume- ... tml#692116

Cheers,
Brent

Last edited by Brent@GMATPrepNow on Sat Nov 30, 2013 11:50 am, edited 1 time in total.

Brent Hanneson - Creator of GMATPrepNow.com

Aman verma: Master | Next Rank: 500 Posts; Posts: 304; Joined: Wed Jan 27, 2010 8:35 amFollowed by: 3 members; Location: International Space Station; Thanked: 11 times

by Aman verma » Sat Nov 30, 2013 11:15 am

OA[spoiler](B)2/3[/spoiler].

Good Night!

800. Arjun's-Bird-Eye

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Sat Nov 30, 2013 11:52 am

Ha - after all of that work, I didn't interpret my own diagram correctly

I edited the last sentence accordingly.

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

telberrak: Newbie | Next Rank: 10 Posts; Posts: 7; Joined: Tue Apr 19, 2011 2:46 am; Location: London; Thanked: 1 times

by telberrak » Fri May 16, 2014 1:27 am

Event A : pro Aam-Aadmi
Event B : pro Aam-Aurat

pick up a pro Aam-Aadmi knowing he's a pro Aam-Aurat is P(A|B)

Probability of A knowing B (non-independent events) is P(A|B) = P(A and B)/P(B)
P(A and B) = 20%
P(B) = 30%

==> P(A|B) = 20%/30% = 2/3

Saifuddin Kamran: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Sat Nov 10, 2018 2:51 pm

GMAT Official Guide 2019 Which of the following statements

by Saifuddin Kamran » Sat Nov 10, 2018 5:45 pm

Can also be solved using Venn Diagrams.
First fill in the overlapping information i.e. 20% here

Then the difference between the total Aam Admi and the overlapping
45% - 20% = 25%

and then the difference between the total Aam Aurat and the overlapping
30% - 20% = 10%

The total possible events in the probability question is " if it is known that he supports the Aam-Aurat Party.", that is 30%

Here the overlapping is 20% So the Probability =20%/30%

Or P = 2/3
Answer B

Saifuddin Kamran
www.simplystudies.com.au
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fskilnik@GMATH: GMAT Instructor; Posts: 1449; Joined: Sat Oct 09, 2010 2:16 pmFollowed by: 33 members; Thanked: 59 times

by fskilnik@GMATH » Sun Nov 11, 2018 6:21 am

Aman verma wrote:In the upcoming Delhi Elections only two major parties are fighting the elections-The Aam-Aadmi Party headed by Arvind kejriwal and The Aam-Aurat party headed by Dr. Sanjay HarshaVardan. 45% of the population support the Aam-Aadmi Party and 30% of the population support The Aam-Aurat Party and 20% of the population support both the parties. One citizen is selected at random from the population named Aman Verma. Find the probability that he supports the Aam-Admi party if it is known that he supports the Aam-Aurat Party.

(A)1/3

(B)2/3

(C)5/6

(D)4/7

(E)5/9

\[? = \frac{{{\text{Aurat}}\,{\text{and}}\,\,{\text{Aadmi}}}}{{{\text{Aurat}}}} = \frac{{20}}{{30}} = \frac{2}{3}\]

This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.

Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
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