A lock is opened using a sequence of three numbers. The numbers range from 0 to 39, inclusive, and cannot be repeated within the sequence.What is the probability that all the numbers in the sequence are even? Express your answer as a percent and round to the nearest whole number.

There are 20 even numbers from 0 through 39. Because numbers cannot repeat, the probabilities for the three positions are 20/40, then 19/39, then 18/38. Multiplying gives about 0.115, or 11.5%, which rounds to 12%. The correct choice is 12%.

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