A password to a certain database consists of digits that cannot be repeated. If the password is known to consist of at least 8 digits and it takes 12 seconds to try one combination, what is the amount of time, in minutes, necessary to guarantee access to database?
Correct answer: D
Explanation
Total # of passwords possible for 8 digits is P810=10!2
Total # of passwords possible for 9 digits is P910=10!
Total # of passwords possible for 10 digits is P1010=10!
Time needed to guarantee access to database is (10!2+10!+10!)∗15=10!2 minutes.
D.
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