Help on General GMAT Questions

Question

Ten years ago, scientists predicted that the animal z would become extinct in t years. What is t?

(1) Animal z became extinct 4 years ago.

(2) If the scientists had extended their extinction prediction for animal z by 3 years, their prediction would have been incorrect by 2 years.

The answer is said to be E but I don't see how A is insufficient.

VeritasPrepDennis · Answer

JRAppz -

The question asks what the timeframe was that the experts predicted animal z would become extinct. That is t.
Stmt 1) tells us only that animal z became extinct 4 years ago. It tells us nothing about what the experts predicted so it is NOT SUFFICIENT.
Stmt 2) tells us that if if the experts extended t by 3 years it would have been incorrect by 2 years. By itself, we cannot determine what t is so it is NOT SUFFICIENT

Now, taken together, we know that animal z became extinct 6 years after the experts made their prediction, and if that prediction had been extended by 3 years, it still would have been off by 2 years. In this case, the experts could have predicted z would have been extinct in 1 year or extinct 5 years (was extinct in 6, so 1 +3 = 4 (off by two years), or 5 + 3 = 8 (again, off by two years). Since we cannot determine the value of t, the Stmts together are NOT SUFFICIENT. Correct answer is E.
St

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