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

Numbers less than 5 are 1, 2, 3, and 4, so there are 4 favorable outcomes. The die has 10 equally likely outcomes, giving a probability of 4/10 = 2/5. Choice B, P(less than 5) = 2/5, is correct.

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