This problem is tricky because it says 'could be,' not 'what is.' That word signals that the two events are NOT necessarily independent — so we can't just multiply the probabilities.
Since we don't know the exact relationship between Aaron and Bryce's elections, the probability of BOTH being elected (P(A and B)) must fall within a specific range.
Here's the key principle:The MAXIMUM P(A and B) can be is the smaller of the two individual probabilities. Both can't win together more often than either one wins alone. So the max = min(
2/3,
3/5) =
3/5.
The MINIMUM P(A and B) can be comes from the idea that their combined probability can't exceed
1. Using the
inclusion-exclusion formula: P(A) + P(B) -
1 =
2/3 +
3/5 -
1 =
10/15 +
9/15 -
15/15 =
4/15. (If this were negative, the minimum would be
0.)
So P(A and B) must be between
4/15 and
3/5, which is roughly between
0.267 and
0.600.
Now let's check each option:I. 1/2 =
0.500 — This falls between
0.267 and
0.600.
YES, this works.II. 1/5 =
0.200 — This is BELOW the minimum of
0.267.
NO, this is too small. It would mean they win together less often than is mathematically possible.
III. 13/20 =
0.650 — This is ABOVE the maximum of
0.600.
NO, this is too large. They can't both win more often than Bryce wins alone (
3/5).
Only I works, so the answer is
B.
The common mistake here is assuming the events are independent and calculating
2/3 ×
3/5 =
2/5 as the only possible answer. When a problem says 'could be,' always think about the full range of possible values.
Answer: B