Answer: 5 bits.
Step-by-step explanation:
If we need to encode 27 characters, we will need 27 distinct symbols.
If we want to use binary numbers, that can take only one of two values (1 or 0), we need a number of bits which possible combinations, add to at least 27.
The minimum number of bits needed to represent 27 combinations, is the least power of 2, greater than 27, i.e., 2⁵ = 32.
So, it will needed at least 5 bits to represent the 26 letters of the alphabet plus a space-a total of 27 characters.