This is a tricky one. Ten years ago, scientists predicted that a certain animal would become extinct in t years. The question does not ask when the animal actually became extinct. Rather, it asks for the value of t, the hypothesis as to when the animal would become extinct.
When dealing with a timeline problem, you might want to sketch a number line to help keep the details straight. In this case, not much has been given yet, so see how the statements play out.
(1) INSUFFICIENT: The question asks for the prediction about the length of time until extinction, not the actual time of extinction.
(2) INSUFFICIENT: The statement provides some information about the relationship between the prediction and the actual time of extinction, but it provides no real values to anchor any of the information to the timeline.
If you sketch a numberline (0 to 10 for the 10 years) and try to place the information on it, there's no starting point. Since you don't know t and you don't know the actual time of extinction, you don't know where to place t + 3.
(1) AND (2) INSUFFICIENT: Now you have an anchor point on the numberline. Animal Z became extinct 4 years ago, or 6 years into the ten-year timeline. Keep sketching. Can you place all of the other information in one definitive way?
It turns out that the information allows for two different possibilities. Place the Start (Year 0) and the known year, Extinction (Year 6), first.
If t + 3 is off by two years from the actual extinction year (Year 6), then t + 3 could be 2 years before extinction during Year 4, in which case t would be Year 1.
| Case 1: |
| Start | t | t + 3 | extinction |
| Year 0 | Year 1 | Year 4 | Year 6 |
However, t + 3 could also fall two years after extinction. The problem says only that t + 3 is off by 2 years; it doesn't say whether the prediction was two years too early or two years too late.
If the prediction was 2 years too late, then t + 3 would be Year 8 and t would be Year 5.
| Case 2: |
| Start | t | extinction | t + 3 |
| Year 0 | Year 5 | Year 6 | Year 8 |
Since there are two possible values for t, the information is insufficient to answer the question. The correct answer is (E): Nothing is sufficient, even if you use both statements given.
