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# Probability

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Manager
Joined: 13 May 2017
Posts: 103
Location: Finland
Concentration: Accounting, Entrepreneurship
GMAT 1: 530 Q42 V22
GPA: 3.14
WE: Account Management (Entertainment and Sports)

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13 May 2017, 12:48
Can someone help out here please? I'm not managing getting the right answer.

I'm quite lost at probability, combinatorics questions. For now finished Manhattan prep Math parts and about to continue with the verbal. But I feel I need something extra for this topic. May I ask your recommendation how to make prob/combinatorics a stronger skill?

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Manager
Joined: 13 May 2017
Posts: 103
Location: Finland
Concentration: Accounting, Entrepreneurship
GMAT 1: 530 Q42 V22
GPA: 3.14
WE: Account Management (Entertainment and Sports)

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13 May 2017, 12:49

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Status: Greatness begins beyond your comfort zone
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Location: India
Concentration: General Management, Strategy
Schools: Kelley '20, ISB '19
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13 May 2017, 20:56
1
rencsee wrote:
Can someone help out here please? I'm not managing getting the right answer.

I'm quite lost at probability, combinatorics questions. For now finished Manhattan prep Math parts and about to continue with the verbal. But I feel I need something extra for this topic. May I ask your recommendation how to make prob/combinatorics a stronger skill?

Sent from my SM-G920F using GMAT Club Forum mobile app

Hi rencsee ,
Once you are clear with basics of counting and combinatorics, you can attempt the GMAT Club tests.
Probability of getting on the base, P(b) = 1/4
Probability of not getting to the base, P(b') = 1- 1/4 = 3/4

Number of times the player comes to bat = 5
Probability that player gets on base 3 or 4 times
=5C3 * $$(1/4)^3$$ * $$(3/4)^2$$+ 5C4 * $$(1/4)^4$$ * (3/4)
= (10 * 3* 3 + 5* 3 ) /1024
=(90+15)/1024
=105/1024
=.10
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Manager
Joined: 13 May 2017
Posts: 103
Location: Finland
Concentration: Accounting, Entrepreneurship
GMAT 1: 530 Q42 V22
GPA: 3.14
WE: Account Management (Entertainment and Sports)

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14 May 2017, 00:44
Skywalker18 wrote:
rencsee wrote:
Can someone help out here please? I'm not managing getting the right answer.

I'm quite lost at probability, combinatorics questions. For now finished Manhattan prep Math parts and about to continue with the verbal. But I feel I need something extra for this topic. May I ask your recommendation how to make prob/combinatorics a stronger skill?

Sent from my SM-G920F using GMAT Club Forum mobile app

Hi rencsee ,
Once you are clear with basics of counting and combinatorics, you can attempt the GMAT Club tests.
Probability of getting on the base, P(b) = 1/4
Probability of not getting to the base, P(b') = 1- 1/4 = 3/4

Number of times the player comes to bat = 5
Probability that player gets on base 3 or 4 times
=5C3 * $$(1/4)^3$$ * $$(3/4)^2$$+ 5C4 * $$(1/4)^4$$ * (3/4)
= (10 * 3* 3 + 5* 3 ) /1024
=(90+15)/1024
=105/1024
=.10

Hi Skywalker18,
Thanks for your reply. I got it. Actually I was using the same method but miscalculated. Maybe it was to late for my brain. I will check Gmat Club Test.

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Manhattan Prep Instructor
Joined: 04 Dec 2015
Posts: 689
GMAT 1: 790 Q51 V49
GRE 1: Q170 V170

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17 May 2017, 13:11
Here's something I recently wrote about learning to handle combinatorics. (There are three articles in the series, so click on all of the links). It's not an exhaustive introduction, but it should get you going in the right direction.

https://www.manhattanprep.com/gmat/blog ... cs-part-1/
https://www.manhattanprep.com/gmat/blog ... cs-part-2/
https://www.manhattanprep.com/gmat/blog ... cs-part-3/
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29 Jan 2019, 14:17
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Probability   [#permalink] 29 Jan 2019, 14:17
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