Question 1132130
i would think D because the probability of getting picked for either project is the same and it ensure that 20 go to one project and 20 go to another.


with A, there is no guarantee that there will be exactly 20 positive numbers and 20 negative numbers.


with C, there is no guarantee that there will be exactly 20 even numbers and 20 odd numbers.


it adds a tcomplexity to the decision.


with D, you have 40 slots and are randomly picking 20 for one or the other project.
everybody has the same chance of being picked or not picked out of the 20 draws.
it's simpler with no complications of what to do if more than 20 are picked for one project or the other, as can happen with A and C.


i'd go with D.


for example, with A, it's possible that 40 students all get positive numbers (not likely, but possible).


since only 20 can go to one project, then you would take the first 20 that has positive numbers.


but which 20?


another decision has to be made to decide which 20 are selected that may or may not be randomly executed.


option D avoids that complexity.


as long as the balls were randomly selected, there is no possibility of bias and you only get 20 for one project with the rest for the other project.