Strickler WMS  -  8th Grade Math
  • Home
  • Number System
    • 8.NS.1 Rational and Irrational Numbers
    • 8.NS.2 Approximations of Square and Cube Roots >
      • Golden Ratio
  • Expressions and Equations
    • Exponents (8.EE.1 - 8.EE.2)
    • Scientific Notation (8.EE.3 - 8.EE.4)
    • 8.EE.5 Graph and Compare Proportional Relationships
    • 8.EE.6 Find the Equation of a Line
    • Linear Equations (8.EE.7 - 8.EE.8)
  • Functions
    • 8.F.1 Input and Output
    • 8.F.2 Compare Two Functions
    • 8.F.3 Examples of Functions
    • 8.F.4 Constructing and Interpreting Functions
    • 8.F.5 Graphing and Analyzing Functions
  • Geometry
    • Transformations (8.G.1 - 8.G.4)
    • 8.G.5 Angle Relationships
    • Pythagorean Theorem (8.G.6 - 8.G.8)
    • 8.G.9 Volume
  • Statistics and Probability
    • Data Analysis and Probability >
      • Line Plots and Frequency Tables
      • Box-and-Whisker Plots
      • Scatter Plots
      • Permutations and Combinations
      • Experimental Probability
      • Simple Random Samples
  • Algebra I
  • Baseball

Permutations

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For permutations ORDER MATTERS!  Lets say 4 people (A,B,C,D) are sitting in four chairs.  How many different ways can they arrange themselves and not repeat an arrangement?  As you can see there are 6 groupings with A in the first position.  For the second column B is in the first position.  Then C and D take their turns being in the first chair.   The answer is 24 arrangements.  This can also be done by doing 4!.  (4! means Factorial)  Watch the video to learn how to use the permutations formula.

Factorial - a multiplication count down.  Start with the number given and count all the way down to 1.
          4! = 4x3x2x1 = 24
          5! = 5x4x3x2x1 = 120
          6! = 6x5x4x3x2x1 = 720

Combinations

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For Combinations ORDER DOES NOT MATTER!  You are more concerned about the number of people or objects involved instead of the arrangement of the group.

Let's say you have 3 friends but you can only take 2 to the upcoming concert.  How many different ways can you select 2 friends from a group of 3?  If you had 3 friends (Blue, Red, and Green), then you could take:  (Blue with Red) or (Blue with Green) or (Red with Green).  The answer is 3 ways.  Watch the video to find out more.


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