Any code that follows a letter substitution pattern like the one described is considered a Caesar Cipher. Note that in order to decipher a Caesar Cipher, it suffices to find out which letter 'A' was replaced by, as this defines all other substitutions to be made.
A message, written in a 26-letter alphabet, was encoded using a Caesar Cipher. Consider the probability of randomly discovering the pattern used in this encoding, given that any failed attempt must be eliminated in subsequent attempts.
The probability of discovering the pattern of this Caesar Cipher only on the third attempt is given by
