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The combination bike lock has four wheels, each of which has the numbers 0 through 13.
Exactly one combination of numbers (in order) on the wheels (7-2-10-6,) will open the lock.
(a) How many possible combinations of numbers are there on my bike lock?
(b) Suppose that I have forgotten my combination. At random I try 1-2-3-4. What is the probability that the lock will open with this combination?
(c) I try at random 25 different combinations. What is the probability that 1 of these 25 efforts will open the lock?
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(a) ANSWER. There are = 38416 different combinations.
Explanation. There are 14 independent options in each of 4 positions.
(b) ANSWER. Probability P = .
It is true for the combination 1-2-3-4, as well for any other fixed combination.
(c) ANSWER. .
Answered, solved, explained and completed.