COMBINATION and PROBABILITY - references. If you have problems with combination and probability you can use this reference page to find information quickly. I guess my small contribution to the GMATclub community will help other people to crack 800 score. THEORY Combinatorics ] | Probability ] -general: Wiki Combination Wiki Permutation -also: 7-t-10838.html permutation-combinations-coverage-30315.html permutations-order-matters-79661.html - how to distinguish Permutations from Combinations -question collections: pc-probability-download-57156.html NOTES FROM WALKER #1. Com-prob problems always have a few different solutions. Try to solve the problems in many ways, and that will give you self-reliance. #2. Use enumeration of possibilities for the problems with complex restrictions. #3. "How can I apply here C^n_k or P^n_k ?" - is a wrong question. Always understand what the formulas mean. LINKS easy - 56860 - 6 boys and 4 girls easy - 56779 - 10 red, 5 blue, 12 yellow pills. easy - 56728 - 10 marbles contains 3 red marbles and 7 blue marbles easy - 56446 - 4 people and integers between 1 and 4 easy - 56419 - an iced tea easy - 55984 - a contest consists of n questions easy - 55939 - 15 chess players easy - 55734 - 3 candidates for a university easy - 55689 - a pack of candy (2) easy - 55644 - a five-question true/false section easy - 55515 - a pack of candy easy - 54481 - red and blue chips medium - 58914 - a junior class has 1,000 students and a senior class has 800 students medium - 58887 - that include Michael also include Anthony medium - 58742 - 2 couples and 1person are seated in a row medium - 58675 - n(n + 1)(n + 2) is divisible by 8 medium - 58670 - Probability of Winning medium - 58640 - 4 people out of the 12 meried couples medium - 58629 - two ineger sets medium - 58609 - 9 people in the room medium - 58529 - 2 objects collide on a cube medium - 58521 - DS: heads than tails medium - 58476 - Marco and Maria toss a coin three times medium - 58360 - two ineger sets (2) medium - 58357 - coin is flipped 5 times medium - 58352 - 11 women and 9 men in a certain club medium - 58350 - DS: 10 light bulbs medium - 58233 - SQUARE medium - 58187 - A certain company assigns employees to offices medium - 58160 - 3 people are to be selected out of 8 people medium - 58095 - Bob are among the 5 participants in a cycling race medium - 58016 - 3 people is to be selected from 5 married couples medium - 57997 - junior class has 1000 students and senior class has 800 students medium - 57981 - positions at univeristy medium - 57980 - women and men of 10 employees medium - 57957 - rain on any given day in City X medium - 57916 - a and b from a set of 4 consecutive integers medium - 57882 - Anthony and Michael sit on the six-member board of directors for company X medium - 57799 - A fair die is rolled once and a fair coin is flipped once medium - 57695 - 3 dwarves and 3 Elves medium - 57645 - A contest will consist of n questions medium - 57629 - coin medium - 57615 - A jar contains b black, w white, and r red marbles medium - 57601 - GMPJBC medium - 57577 - 5 people are to be seated around a circular table medium - 57554 - Coach Miller medium - 57332 - A coach will make 3 substitutions medium - 56826 - 7 people and friendship medium - 56814 - coin with sides marked heads and tails medium - 56814 - tails side up more than five times medium - 56812 - a election in Burghtown. medium - 56709 - A set consist of 2n-1 element medium - 56705 - 25 lines medium - 56681 - 2 numbers from 1,2,3,4,5 medium - 56590 - 2 red and 3 blue marbles medium - 56586 - different colors from 6 flowers. medium - 56585 - 4 particular flowers of 8 different flowers medium - 56572 - five-digit numbers medium - 56557 - a committee of 4 distinct pairs of brothers and sisters medium - 56556 - three letters taken from letters (a,a,b,b,c,c,d) medium - 56530 - 12 playing cards medium - 56530 - 4 cards of 12 cards medium - 56446 - 4 people choose an integer between 1 and 4, inclusive. medium - 56445 - 5 of 7 models medium - 56443 - Two couples and one single person in a row of five chairs. medium - 56349 - 3 girls and 4 boys in a row medium - 56327 - shirts, shoes, pants medium - 56122 - Six mobsters: Frankie behind Joey medium - 56037 - a team from men and women medium - 55870 - 3 cars medium - 55823 - 4 senior partners and 6 junior partners medium - 55811 - 5 women are in a race medium - 55803 - a committee from 4 married couples medium - 55764 - 100 numbered cubes medium - 55743 - A and B stocks medium - 55694 - Two fair dices medium - 55673 - 3 different marbles medium - 55644 - GMATT answers medium - 55617 - 4 guys, 2 girls and 14 dogs. medium - 55509 - A committee of 3 people from 4 couples medium - 55504 - Ways from A to D medium - 55472 - 4 pairs of brothers and sisters medium - 55427 - 4 books fom 2 paperback and 6 hardback books medium - 55421 - the probability that n(n+1)(n+2) will be divisible by 8 medium - 55413 - 3-digit integer medium - 55410 - A committee from 5 military officers and 9 civilians. medium - 55383 - 4 physics, 2 math and 3 chemistry books medium - 55372 - My name is AJEET medium - 55369 - 8 friends want to play doubles tennis medium - 55366 - The most expensive two books medium - 55340 - trhee letters from seven different postboxes medium - 55311 - 6 cards medium - 55253 - Rich has 3 green, 2 red and 3 blue balls in a bag medium - 55141 - A bowl contains white and black balls. medium - 55071 - 10 bottles of alcohol medium - 55054 - 3 sniper's shoots medium - 54794 - a fantasy football game medium - 54650 - 6 cards medium - 54332 - Bob and Jen in a race medium - 53774 - The choir consists of 5 boys and 6 girls medium - 50488 - 5 digit numbers medium - 45753 - a committe of 3 of 6 people medium - 41464 - deck contains 2 blue, 2 red, 2 yellow, and 2 green cards medium - 19685 - 5 digit numbers formed using the digits 0, 1, 2, 3, 4, 5 medium - 15366 - Mary and Joe throw three dice each medium - 59065 - A 4-letter code hard - 58616 - PS Standard deviation + probabilities hard - 57713 - the total number of permutations of n different things hard - 57447 - A fair coin is tossed 10 times hard - 57169 - DS: How many subordinates does Marcia Have _______________________________________________ See also: General: https://gmatclub.com/wiki/Tests - Challenges (Online GMAT Tests) https://gmatclub.com/wiki/GMAT_Study_Guide - GMAT Study Guide 1-gmat-timer-56014.html - my GMAT timer Math: 7-t-44300.html - good collection of Math links. \to https://gmatclub.com/forum/7-t-56486.html - Combination-Permutation-Probability quant problems: my list with links 7-t-57156.html - Combination-Permutation-Probability quant problems: list of 55 different question with explanation Amardeep Sharma ] Verbal: 11-t-50635.html - Brutal_SC, Idoms and good tips in Verbal section especially for non-native speakers nervousgmat ] 11-t-28708.html - A very nice thread of grammar use in GMAT with additional materials https://manhattanreview.com/download/MR- ... -Guide.pdf - Manhattan Review Sentence Correction Guide https://manhattanreview.com/download/GMA ... y-List.pdf - GMAT Vocabulary List – Basic Level 11-t-4248.html - SC-Tips anandnk ]

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COMBINATION and PROBABILITY - references. If you have

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gmatdelhi

Hey! Thanks a lot for the effort! What's the source of these questions? Any of them from GMATPrep or Kaplan/MGMAT practice tests???

Possibly.... these are from before the time we started tagging questions and posts.

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gmatdelhi

Hey! Thanks a lot for the effort! What's the source of these questions? Any of them from GMATPrep or Kaplan/MGMAT practice tests???

Possibly.... these are from before the time we started tagging questions and posts.

hello bb,

Where are the materials. I could not find any docs in this page or any links..
I really need those Probability and Combinations docs.Please help..

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28 Dec 2010, 16:07

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jullysabat

gmatdelhi

Hey! Thanks a lot for the effort! What's the source of these questions? Any of them from GMATPrep or Kaplan/MGMAT practice tests???

Possibly.... these are from before the time we started tagging questions and posts.

hello bb,

Where are the materials. I could not find any docs in this page or any links..
I really need those Probability and Combinations docs.Please help..

What docs? There are no docs.

jullysabat

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28 Dec 2010, 17:22

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Possibly.... these are from before the time we started tagging questions and posts.[/quote]

hello bb,

Where are the materials. I could not find any docs in this page or any links..
I really need those Probability and Combinations docs.Please help..[/quote]

What docs? There are no docs.[/quote]

The second post in this page/chain says "thanks for the material" so I was searching for probability/combination material.
pls see the print screen below.

Attachments

abc.png [ 22.91 KiB | Viewed 5083 times ]

anon321

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this is great. thanks

thisguy310

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15 May 2011, 09:48

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thanks so much for sharing this!

Just thought I'd add this link from Khan Academy. I think these walk throughs help explain permutations and combinations as well https://www.khanacademy.org/video/permut ... robability

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Hi all,

@Walker: Many thanks!! I was searching for a good description.
I am struggling with probabilities since...well, since I was at school and during University.
I will go through on this on weekend! :thumbup:

Edit:
Hi all,

I have a problem understanding the probability.

Let us say: In a box, here are 8 Red Ball and 5 White Balls.
How high is the probability to get 2 Red Balls and 2 White Balls?

I have solved this with using the Combinations formula.
$p=\frac{n}{N}$
n--> 2C8 * 2C5
N--> 4C13
I get 40%.

But is there a other approach?

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04 Feb 2012, 10:13

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Great compilation Walker.... :thumbup:

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08 Feb 2012, 06:50

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Combinations, Permutations, and Probability are definitely my weakness. Thanks for sharing all the information and questions.

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21 Feb 2012, 17:38

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Thank you for sharing this! These are some of my weaknesses and I hope to improve them using your links.

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Thanks. As many here, I have also problems understanding the structure of this kind of question.
But I understand now the combination and permutation topic (thanks to MGMAT book). It is just how you count the ways.
Probability is much harder. Even if it is based on counting / enumeration, it is hard to understand a word question (I mean the translation into math).

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much needed. this is just what i needed. my weakest section on the quan side of the house...

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Thank you so much for this! Has helped a lot!

Just a heads up: the following link doesnt work anymore:

medium - 58352 - 11 women and 9 men in a certain club

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Hi,

I have doubts regarding the following questions.Please suggest how to go about it.

1)Using the digits 2,3,4,5,6 find the following:-
a)Sum of all 5 digit nos. that can be formed such that no 2 digits are the same.
b)Sum of all 4 digit nos. that can be formed such that no 2 digits are the same.
c)Sum of all 4 digit nos. that can be formed such that digits can be repeated.

The book I am referring to has used the below formula to solve the above question:_

(2+3+4+5+6)= sum of digits
(11111)= As many 1's as there are digits in the number.
(4!) =no. of times any digit appears in any place.

But I don't understand the exact usage of the formula.

2)A group of 11 people went to a party.There were 5 girls and 6 boys who were seated on a rectangular table with 6 chairs on either side of the longer edge.
a) What is the total no. of ways the group could be seated(Sides are indistinguishable)?
b)What is the no. of ways they can be seated so that all the 5 girls were sitting on the same side?

Thanks in advance.

PGTLrowanhand

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Hi everyone,

Here is the list of Probability resources available on my site: https://privategmattutor.london/gmat-probability-resources-articles-books-and-videos/

Here are the Combinatorics resources: https://privategmattutor.london/category/gmat-combinatorics/

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Hello from the GMAT Club BumpBot!

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