OG详解-OG7 数学2 Q5

Choice B is correct. The probability of selecting a positive number is the number of positive numbers in the data set divided by the total number of numbers in the data set. There is 1 positive number in this data set. There are 3 total numbers in this data set. Thus, if a number from this data set is selected at random, the probability of selecting a positive number is 1​3​.
Choice A is incorrect and may result from conceptual or calculation errors. Choice C is incorrect. This is the probability of selecting a negative number from this data set. Choice D is incorrect and may result from conceptual or calculation errors.