Answer: 0.38%
Explanation:
Since there is one letter and one number from 0-9, there are 26 possible letters and 10 possible numbers. Therefore, the total number of lock combinations possible is:
26 letters x 10 numbers = 260 combinations
b. Since Elpha has no knowledge of the correct combination and each combination has an equal chance of being correct, the probability of guessing the correct combination on the first try is:
1 / 260 = 0.003846153846153846
Therefore, the probability of guessing the correct lock combination on the first try is approximately 0.38%.