There are five small cards of the same size, write 1,2,3,4,5 on them respectively, and then put them in the bag to mix well. Take three cards out of the bag each time, record the results, and then put them back into the bag to wash well. If there are three consecutive numbers, they are called "step height". For example, 1,2,3:2,3,4; 3,4,5. What is the probability of "step height"?

There are three combinations of step height, namely 123234345
There are 10 combinations of 5 * 4 * 3 / (3 * 2 * 1) = 3 out of 5 cards
So the probability of step-by-step high is 3 / 10
The answer of the man in front is wrong

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