A researcher plans to identify each participant in a certain medical experiment with a code consisting of either a single letter
or a pair of distinct letters written in alphabetical order. What is the least number of letters that can be used if there are 12 participants, and each participant is to receive a different code?A. 4 B. 5
C. 6
D. 7
E. 8
The code can either be Single letters or 2 letter in alphabetical order
single letter coder are
A
B
C
D
The two letter code are
AB
AC
AD
BA
BC
BD
CD
That is, a total possibility of 10 code which means 4 is not going to work
When E is added then we have AE, BE and the rest . The possibility will be more than 12 so if we have 5 letter then we will have more than enough which means 5 is the answer
