SAT Question 1b8e412e: Probability And Conditional Probability answer and explanation with Desmos solution

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 $\frac{1}{3}$.