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):
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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