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Homework Help: Number of Possible Arrangements (Permutations?)

  1. May 18, 2010 #1
    1. The problem statement, all variables and given/known data
    If a multiple-choice test consists of 5 questions each with 4 possible answers of which only 1 is correct,

    (a) In how many different ways can a student check off one answer to each question?

    (b) In how many different ways can a student check off one answer to each question and get all the answers wrong?


    I feel like if I could get a hint on (a) I could do (b) as well, but I am a little stuck trying to figure out which rule to apply. These are permutations correct? (the arrangement of answers.)

    Or should I just apply the "multiplication rule" somehow?
    Can I get just a hint here?
     
  2. jcsd
  3. May 18, 2010 #2
    a) How many ways are there to answer ONE question? i.e. How many ways are there to PICK/CHOOSE one of the four answers? How many ways are there to do this for 5 questions?
     
  4. May 18, 2010 #3
    Let's denote each answer choice for each question as a, b, c, d.

    So for each question there are 4 different ways to answer. Oh. So it is 4^5 = 1024. So it is the multiplication rule.
     
  5. May 18, 2010 #4
    So I suppose for part (b) since I have (4-1) choices for each, the answer would be (4-1)^5 = 243.
     
  6. May 18, 2010 #5
    Sounds good to me!
     
  7. May 19, 2010 #6
    Thanks homes!
     
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