Problem 6 · 2018 Math Kangaroo
Medium
Logic & Word Problems
The following two statements are true: some aliens are green and all others are purple; green aliens live on Mars only. Which one of the following logical conclusions can be made?
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Answer: E — There are no green aliens on Venus.
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Hint 1 of 2
List exactly what the two true statements force and what they do not.
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Hint 2 of 2
Check each option against 'green aliens live on Mars only'.
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Approach: test each conclusion against the given facts
- Green aliens live on Mars only, so no green alien can be on Venus.
- The colour split (some green, the rest purple) does not force all aliens onto Mars, nor pin purple aliens to Venus.
- Only the statement 'there are no green aliens on Venus' must be true.
- Answer: (E).
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