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Explanation:
The requirements for a probability distribution are this
- The individual probabilities must be between 0 and 1, inclusive of both endpoints. We can say
where p is an individual probability.
- The probabilities must sum to 1.
Condition #1 shown above allows us to rule out choice C due to -0.10 not being in the interval from 0 to 1.
We can also rule out choice D since the probabilities sum to this
0.20+0.15+0.20+0.20+0.20+0.20 = 1.15
The sum is too large. The sum needs to be 1.00 or just 1.
So that leaves choice A or choice B as the possible answer. Both distributions fit conditions #1 and #2 as shown above (I'll let you confirm these facts). However, choice A is ruled out because that distribution is considered fair. Each probability for choice A is equal, so each side of the cube is equally likely to be landed on.
For choice B, the probabilities are different, so we don't have a fair cube here and it is considered loaded or biased.