GED Practice

GED Math Review: Probability of Combination & Permutations

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  1. Sally is packing for a 12-day trip. She wants to be able to mix and match her tops and pants so that she wears a different outfit everyday but doesn't have to pack 12 tops and 12 pairs of pants. Which of the following combinations will give her less to pack but still provide for 12 different outfits?
    • 3 tops, 5 pants 
    • 4 tops, 4 pants 
    • 3 tops, 3 pants 
    • 3 tops, 4 pants
  2. A restaurant offers 3 types of meat, 2 types of potato, 4 types of vegetable, and 5 different desserts. How many meal combinations are there at that restaurant, assuming the patrons pick one of each category? 
    • 24 
    • 120 
    • 30 
    • 240 
  3. A restaurant offers 3 types of meat, 2 types of potato, 4 types of vegetable, and 5 different desserts. What if there was an additional choice in each category: none. Then how many meals would there be?
    • 359
    • 119
    • 59
    • 89
  4. In how many ways can 3 of the 4 letters ABCD be rearranged if order makes a difference?
    • 12
    • 10
    • 24
    • 4
  5. How many ways can 3 of the 4 letters ABCD be picked in any arrangement?
    • 12
    • 10
    • 24
    • 4


Answers:

  1. 3 tops, 4 pants   
    (choices: 3 tops x 4 pants = 12 outfits)
  2. 120 
    (choices: 3 meat x 2 potato x 4 vegetable x 5 dessert = 120 choices)
  3. 359
    (choices: 4 meat including none x 3 potato including none x 5 vegetable including none x 6 dessert including none = 360 choices minus no-meal person)
  4. 24
    (Since order makes a difference, this is a permutation:
    choices: 4 letters x 3 letters x 2 letters = 24 ways)
  5. 4
    (This is a combination: ABC, ABD, ADC, BDC. Any other combination is the same as one of these.)




Reference:
GED Math Test Tutor by Sandra Rush