Problem 21 · 2015 Math Kangaroo
Hard
Logic & Word Problems
casework
The statements (A)–(E) are checked for their truth one after the other. Which of them is the first true statement?
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Answer: D — (B) is false.
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Hint 1 of 2
Start by settling which statements are true, beginning with the one that is plainly true.
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Hint 2 of 2
Then read A, B, C, D in order and stop at the first true one.
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Approach: evaluate the self-referential statements, then scan in order
- (E) '1+1=2' is true; therefore (C) '(E) is false' is false.
- (A) '(C) is true' is false, and (B) '(A) is true' is false.
- (D) '(B) is false' is true — and it is the first true statement read in order (D).
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