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1 hour Combinatorics Video Lesson

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1 hour Combinatorics Video Lesson  [#permalink]

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New post 05 Dec 2014, 08:37
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For anyone struggling to understand combinatorics and how this concept may show up on the exam, please learn these critical insights:

http://www.gmatpill.com/gmat-practice-t ... ons-lesson
Image
The video is 1 hour long and includes multiple examples of questions you will likely see on your test.

It is broken down as follows:

00:00 - Intro
01:00 - Warmup
02:12 - Part 1 Overview: Combinations & Permutations vs Variations
08:35 - Part 1 Details: Picking Teams, Dice, Pocket Pair, Dating
17:21 - Part 2: Apply to GMAT - Word Problem #1
22:13 - Part 2: Apply to GMAT - Word Problem #2
31:34 - Part 2: Apply to GMAT - Word Problem #3
38:04 - Part 3: Poker Probability - Pocket Pair vs Pocket Aces
43:40 - Part 3: Poker Probability - Given Pocket Aces, 3-of-a-Kind?
46:13 - Part 3: Poker Probability - 1-Pair by 5th Flop
49:59 - Part 3: Poker Probability - Full House/Flush
1:00:00 - Conclusion

Note: the Poker part is just for fun - you will not see poker questions on the test. But the prior 3 examples are game for the test.
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Re: 1 hour Combinatorics Video Lesson  [#permalink]

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New post 26 Dec 2014, 09:09
That wasn't very useful for me... You actually need to know quite a bit first in order to follow the video.
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Re: 1 hour Combinatorics Video Lesson  [#permalink]

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New post 26 Dec 2014, 09:16
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pacifist85 wrote:
That wasn't very useful for me... You actually need to know quite a bit first in order to follow the video.


Combinations and probability are advanced topics. One should deal with them only after all other topics covered by the test. Also, before attempting questions, one should go through basics.

Theory on Combinations: math-combinatorics-87345.html

DS questions on Combinations: search.php?search_id=tag&tag_id=31
PS questions on Combinations: search.php?search_id=tag&tag_id=52

Tough and tricky questions on Combinations: hardest-area-questions-probability-and-combinations-101361.html

Theory on probability problems: math-probability-87244.html

All DS probability problems to practice: search.php?search_id=tag&tag_id=33
All PS probability problems to practice: search.php?search_id=tag&tag_id=54

Tough probability questions: hardest-area-questions-probability-and-combinations-101361.html


Hope it helps.
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Re: 1 hour Combinatorics Video Lesson  [#permalink]

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New post 21 Jan 2019, 20:42
GMATPill wrote:
For anyone struggling to understand combinatorics and how this concept may show up on the exam, please learn these critical insights:

http://www.gmatpill.com/gmat-practice-t ... ons-lesson
Image
The video is 1 hour long and includes multiple examples of questions you will likely see on your test.

It is broken down as follows:

00:00 - Intro
01:00 - Warmup
02:12 - Part 1 Overview: Combinations & Permutations vs Variations
08:35 - Part 1 Details: Picking Teams, Dice, Pocket Pair, Dating
17:21 - Part 2: Apply to GMAT - Word Problem #1
22:13 - Part 2: Apply to GMAT - Word Problem #2
31:34 - Part 2: Apply to GMAT - Word Problem #3
38:04 - Part 3: Poker Probability - Pocket Pair vs Pocket Aces
43:40 - Part 3: Poker Probability - Given Pocket Aces, 3-of-a-Kind?
46:13 - Part 3: Poker Probability - 1-Pair by 5th Flop
49:59 - Part 3: Poker Probability - Full House/Flush
1:00:00 - Conclusion

Note: the Poker part is just for fun - you will not see poker questions on the test. But the prior 3 examples are game for the test.


I am stuck with 3 problems and the way they are solved:

1. How many distinct ways can 3 guys vote for those 3 girls? (variations)
Solved by considering the 1st guy can date 3 girls, 2nd guy can date 3 girls as well ...
3*3*3 = 3^3

2. How many potential dates can happen between 3 guys and 3 girls? (combinations)
3c1 + 3c1 + 3c1 = 9

3. How many different ways can 3 guys and 3 girls pair up for a group date of 6 people? (permutations)
3c1 * 2c1 *1c1 = 6

Can someone please help me understand what is the difference between the 3, as it is all about 3 guys choosing 3 girls, and why different methods are used
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Re: 1 hour Combinatorics Video Lesson   [#permalink] 21 Jan 2019, 20:42
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