Question

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

Answer 1

B. 5

Explanation:

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