SOLUTION: How many permutations of 2 item can be selected from a group of 4? ? B) Use the letters A, B, C D to identify the items & list each possibility. c) If random sampling is emplo

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Question 1160357: How many permutations of 2 item can be selected from a group of 4? ?
B) Use the letters A, B, C D to identify the items & list each possibility.
c) If random sampling is employed what is the probability that any particular sample will be selected
is my answer correct below ?
(4!)/(2!) = 12
B) { AB, AC, AD, BA, BC, BD, CA, CB, CD, DA, DB, DC }
Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20849)   (Show Source): You can put this solution on YOUR website!

yes, your answer is correct
Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
.

The formula (4!)/(2!) = 12 produces the correct number/answer 12;

    but the logic behind it is DARK.



The common/normal/regular logic is  

    the number of permutations of 2 items selected from a group of 4 items  is  4*3 = 12.



It says that you can place any of 4 items to the 1-st position

and then to complete the pair by adding any of 3 remaining items.


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