What is the probability of rolling a number less than 5? A ten-sided die with sides numbered 1 through 10 is rolled once.

The ten-sided die has 10 equally likely outcomes. The numbers less than 5 are 1, 2, 3, and 4, so 4 of the 10 outcomes work. Thus the probability is 4/10 = 2/5, which is choice B.

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