Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
Associated Topics || Dr. Math Home || Search Dr. Math

Probability: Permutations and Combinations

Date: 12/10/2002 at 20:27:26
From: Apurva Yeluru
Subject: Probability: Permutations and Combinations

Dr. Math,

I am in eighth grade. We are not doing probability but I am interested 
in it. Last year in our school, we had a probability fair and I could 
not understand it very well. Now I can! I know what probability is and 
what permutations are and what combinations are. But this is the part 
where I am stuck: How is probability related to permutations and 

I would be delighted if you replied.


Date: 12/11/2002 at 11:50:25
From: Doctor Ian

Hi Apurva,

The relationship is that when you want to compute the probability that
something will happen, you do this:

      how many ways can the thing happen?
  p = -----------------------------------
      how many ways can anything happen? 

Combinations and permutations are useful for computing the numerator
and denominator of this fraction. For example, if you want to know
the probability of drawing two pairs in poker, that's 

      the number of combinations of 5 cards with 2 pairs
  p = --------------------------------------------------
      the number of combinations of 5 cards

In other words, when you're computing probabilities, you often need to
compute the number of ways that things can be selected from a group
(combinations) or ordered within a group (permutations). 

Does that make sense? 

- Doctor Ian, The Math Forum

Date: 12/14/2002 at 09:57:29
From: Apurva Yeluru
Subject: Thank you (Probability: Permutations and Combinations)

Doctor Ian,

Thank you for the answer. It really does make sense. 
Now I think I can solve some problems!

Associated Topics:
High School Permutations and Combinations
High School Probability
Middle School Probability

Search the Dr. Math Library:

Find items containing (put spaces between keywords):
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

Math Forum Home || Math Library || Quick Reference || Math Forum Search

Ask Dr. MathTM
© 1994-2015 The Math Forum