Answer:
Laura needs to try 36 more times before the lock is sure to open.
Explanation:
Alright, with a three digit lock, there are 9 possible numbers for each digit:
1, 2, 3, 4, 5, 6, 7, 8, and 9.
Since the first one is 3, lets move onto the second digit, which is prime.
Of the numbers between 1-9,
2, 3, 5, and 7 are prime.
With the last digit, it can be any number 1-9.
With all of this, there are 4 combos left for the second digit then 9 combos for the third digit. Therefore, there would be 36 possible combinations as 4 * 9 =36.