Combination: number of ways of picking unordered outcomes from certain possibilities

STEPS FOR COMBINATION PROBLEMS

Solving combinations requires three steps:

1) Determine the number of categories
2) Determine the number of options in each category
3) Multiply the number of possible options

SAMPLE PRACTICE QUESTIONS FOR COMBINATIONS

1. Each day, Janet dresses her child with 1 of 7 skirts, 1 of 10 shirts, and 1 of 6 pairs of shoes. What is the total number of different outfits that Janet’s child can wear?

      Solution
      1) # of categories = skirts, shirts, pairs of shoes
      2) # of options = 7 , 10 , 6
      3) Multiply the number of options
      4) She has 420 outfits.

2. The combination for a lock is a sequence of 3 numbers, each of which is between 0 and 9. If none of the 3 numbers in the sequence can be the same and the first number cannot be 0, then how many different combinations for the lock are possible?

     Solution
      1) # of categories = 3 (a × b × c)
      2) # of options
            a) 9 options (# 0, leaving 1-9)
            b) 9 options (first # can’t be repeated)
            c) 8 options (first 2 #s can’t be repeated)
      3) Multiply the number of options
      4) 9 × 9 × 8 = 648. The lock has 648 combinations.

SAT Math: Combination Problems

Lesson Includes:

—Math Terms for Combination Questions

—Steps for Combination Problems

—Sample Practice Questions

—Practice Questions

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COMBINATION MATH QUIZ

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