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Need help with counting problems

  1. Mar 25, 2016 #1

    Math_QED

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    Homework Helper

    1. The problem statement, all variables and given/known data

    Counting problems are a very tough subject to me, so if someone could give me tips, examples explaining what's really happening, that would be great.

    2. Relevant equations

    I know what permutations, variations, combinations, ... are. The problems involving only one of those are do-able, but those that combine more than one are the difficult ones for me.

    3. The attempt at a solution

    I do not really have a certain problem as I find most exercises rather difficult.


    Thanks in advance.
     
  2. jcsd
  3. Mar 25, 2016 #2

    jedishrfu

    Staff: Mentor

    You could check out Khan Academy and watch videos on the subject;

    https://www.khanacademy.org/math/precalculus/prob-comb/combinations/v/introduction-to-combinations

    Start with a simple problem:

    How many 3 letter words can I make?

    How many 3 letter words can I make with the first letter is a consonant?

    How many 3 letter words can I make with the first letter a consonant and the second letter a vowel?

    then do the same problems with the restriction that no letter can be repeated.

    Think up your own problems and post them here with your work for us to comment on.
     
  4. Mar 25, 2016 #3

    jedishrfu

    Staff: Mentor

    Here's some more videos from MathIsPower4U.com under Algebra 2:

    https://dl.dropboxusercontent.com/u/28928849/Webpages/Algebra2VideoLibraryTable.htm

    under column 3 you'll find this list of videos:

    Counting and Probability
    Counting Principle

    The Counting Principle
    Ex: Determine the Number of Possible Outfits - Counting Principle
    Ex: Determine the Number of Three Letter Codes - Counting Principle
    Ex: Determine the Outcomes Rolling Colored Dice - Counting Principle
    Ex: Determine the Number of Possible License Plates - Counting Principle
    Ex: Determine the Number of Ways to Complete a True/False Test - Counting Principle

    Permutations and Combinations

    Permutations
    Ex: Evaluate a Combination and a Permutation - (n,r)
    Ex: Evaluate a Combination and a Permutation - (n,1)
    Ex: Determine the Number of Ways Six Runners Can Finish - Counting/Permutation
    Ex: Determine the Possible Number of 4 Color Striped Flags (Permutation)
    Ex: Determine the Possible Number of of Ways 255 Contestants can Win 3 Prizes (Permutation)
    Ex1: Determine the Number of Permutations With Repeated Items
    Ex2: Determine the Number of Permutations With Repeated Items
    Combinations
    Ex: Determine the Number of Ways 6 Books can be Selected from 9 Books (Combination)
    Ex: Determine the Number of Ways 3 Varieties can be Selected from 12 (Combination)
    Ex: Determine the Number of 4 Topping Pizzas from 14 Toppings (Combination)
    Ex: Determine the Number of 4 Card Hands from 52 Cards
    Solving Counting Problems
     
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