Question

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?

Answer 1

Knowledge that it has been 1,200 years since the last 100 meter asteroid impact does not change the annual probability of such an event. Each year's likelihood remains independent and unchanged, at 1 in 1,000 for such an impact. For the calculation provided, a mass extinction event has a probability of 1 in 100,000 to occur within the next 50 years.

Step-by-step explanation:

The question provided is asking for the assessment of risk based on given probabilities of asteroid impacts. With an annual probability of 1 in 1,000 for a 100 meter asteroid impact, knowing that it has been 1,200 years since the last such event does not change the risk assessment for the current or next year. This is because each year is an independent event when it comes to asteroid impacts. As for the example calculation provided within the question text, if a major impact event occurs on average once every 5 million years, the probability of such an event occurring within the next 50 years is calculated by dividing 50 by 5 million, which results in a probability of 0.00001, or 1 in 100,000.