Two new computer codes are being developed to prevent unauthorized access to classified information. The first consists of six digits ( each chosen from 0 to 9); the second consists of three digits (from 0 to 9) followed by two letters ( A to Z), excluding I and O).
I) which code is better at preventing unauthorized access ( defined as breaking the code in one attempt)?
ii) if both codes are implemented, the first followed by the second, what is the probability of gaining access in a single attempt?