The impact of a 100 meter asteroid could kill many people if it struck a major city. Suppose the probability of such an impact in any single year is 1 in 1,000, and suppose we know (somehow) that it has been 1200 years since the last impact. What would that tell us?
A) We are overdue for such an impact, so we should expect to be hit by something even larger during the next few years.
B) The prediction must be wrong, since the time since the last impact has been 1200 years.
C) We are now due for such an impact, so the actual probability for the coming year must be much higher than 1 in 1000.
D) Nothing, we would still presume that the chance of such an impact during the next year is 1 in 1000.

Question

Quizplus · Accepted Answer

The fact that it has been 1200 years since the last impact does not affect the probability of an impact in the coming year. The probability of an impact in any single year is still 1 in 1000, and this probability does not change over time. Therefore, given this information, the best choice is D, which states that we would still presume that the chance of such an impact during the next year is 1 in 1000.

The Impact of a 100 Meter Asteroid Could Kill Many