JNU SSS 2013 Question 21: Logic and proof techniques
A number of species faced extinction during the Mesozoic era. Species R, S, T, U, V, W and X were species that all became extinct during this era and scientists have determined that their extinction occurred based on the following constraints :
W became extinct before X.
U became extinct after T.
S became extinct before T.
X became extinct before U.
V became extinct after U.
S became extinct before W.
R became extinct before S.
If the constraints were changed and X were not required to become extinct before U, then which of the following is a possible order for the species’ extinction?
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A number of species faced extinction during the Mesozoic era. Species R, S, T, U, V, W and X were species that all became extinct during this era and scientists have determined that their extinction occurred based on the following constraints: W became extinct before X. U became extinct after T. S became extinct before T. X became extinct before U. V became extinct after U. S became extinct before W. R became extinct before S. If the constraints were changed and X were not required to become extinct before U, then which of the following is a possible order for the species’ extinction? (A) W, R, S, T, U, X, V (B) R, S, X, W, T, U, V (C) R, X, S, W, T, U, V (D) R, S, T, U, V, W, X
Logic and proof techniques has come up 73 times in 3 exams since 2004.
What this question tests
This question is on Logical reasoning puzzles, part of Logic and proof techniques in Mathematics.
Deduction problems that ask what must follow from a set of constraints.
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