SOLUTION: number of ways that two letters can be selected from {A, B, C, D} if order in the sample is to be considered. List the possible samples. My answer-

Question 162709: number of ways that two letters can be selected from {A, B, C, D} if order in the sample is to be considered. List the possible samples.
My answer-
AA BA CA DA
AB BB CB DB
AC BC CC DC
AD BD CD DD
Thanks

Answer by Edwin McCravy(20056) (Show Source): You can put this solution on YOUR website!

number of ways that two letters can be selected from {A, B, C, D} if order in the sample is to be considered. List the possible samples. 


Your answer is wrong because you cannot duplicate a member of a set, 
such as AA.  There is but one A to choose.  The permutations are 

AB
AC
AD
BA
BC
BD
CA
CB
CD
DA
DB
DC

4 place 2.   Permutations of 4 things taken two at a time.

Edwin

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