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We have looked at various facts about hurricanes in previous chapters. Suppose we find that the arrivals of hurricanes can be modeled by a Poisson distribution with mean 2.45 . a. What's the probability of no hurricanes next year? b. What's the probability that during the next two years, there's exactly 1 hurricane?

Short Answer

Expert verified
a. The probability of no hurricanes next year is \( e^{-2.45} \). b. The probability of exactly 1 hurricane in the next two years is \( e^{-4.9} * 4.9 \).

Step by step solution

01

Calculate the probability of no hurricanes next year

To find the probability of no hurricanes next year, we apply the formula for the Poisson probability: \(P(X=k; \lambda) = e^{-\lambda} * (\lambda^k) / k!\), where k is the number of events we're interested in, and here k=0. So, the calculation will look like this: \(P(X=0; \lambda=2.45) = e^{-2.45} * ((2.45)^0) / (0!)\)
02

Evaluate the previous step and get the final result for part a

We must plug in the values, but we must be mindful of the zero factorial, which equals 1. So, the calculation results in: \(P(X=0; \lambda=2.45) = e^{-2.45} * 1 / 1\)
03

Calculate the probability of exactly 1 hurricane in the next two years

The mean of hurricanes per 2 years is 2.45*2=4.9. In this part, we are interested in exactly one hurricane occurrence in two years, so k=1. The calculation will be: \(P(X=1; \lambda=4.9) = e^{-4.9} * ((4.9)^1) / (1!)\)
04

Evaluate the previous step and get the final result for part b

This step is again a matter of plugging in the values and simplifying where possible. In this case, the factorial of one also equals one, so the result is: \(P(X=1; \lambda=4.9) = e^{-4.9} * 4.9 / 1\)

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Hurricane Probability
Understanding the probability of hurricanes occurring during a specific time period is crucial for preparing and planning. In the context of statistics, hurricane probability often deals with the likelihood of hurricanes striking a certain region within a given time frame using mathematical models.

One such model is the Poisson distribution, which is particularly useful for modeling events that occur independently over time, such as hurricanes. Unlike deterministic models that provide specific predictions, probability models like the Poisson distribution offer a way to estimate the chances of different possible outcomes based on historical data.

Recognizing the frequency and probability of hurricane events helps governments and communities plan for disaster management and resilience strategies. Using these statistical models can help in anticipating potential changes in hurricane patterns, especially in the context of climate change.
Statistical Models
Statistical models like the Poisson distribution help us understand and predict the behavior of seemingly random events. The Poisson distribution is particularly handy when analyzing rare events and is often used in fields such as meteorology and epidemiology.

This model assumes that these events occur independently and the rate (mean number of occurrences) is constant over time. Importantly, for a Poisson random variable, the number of events in any given interval is independent of the number of events in any other non-overlapping interval. This trait makes it suitable for estimating occurrences like hurricanes over a specific period.

The formula for the Poisson distribution is:
  • \( P(X=k; \lambda) = \frac{e^{-\lambda} \cdot \lambda^k}{k!} \)
where:
  • \( k \) is the actual number of occurrences.
  • \( \lambda \) is the average number of hurricanes (mean).
  • \( e \) is Euler's number, the base of the natural logarithm.
These components make the Poisson distribution a powerful tool for addressing real-world phenomena like hurricane tracking.
Probability Calculation
Calculating probability using the Poisson model can seem daunting, but it's manageable by breaking it down into steps. Whether calculating the likelihood of what seems like an unlikely event (such as no hurricanes in a hurricane-prone area) or a specific number of occurrences, it entails evaluating the formula appropriately.

To find the probability of no hurricanes in a year given a mean of 2.45 hurricanes, the Poisson probability formula is applied with \( k = 0 \):
  • \( P(X=0; \lambda=2.45) = \frac{e^{-2.45} \cdot (2.45)^0}{0!} = e^{-2.45} \)
This indicates the chance of experiencing zero hurricanes within that year. Similarly, if you wish to find the probability of exactly one hurricane within two years, where the average rate changes to 4.9 due to extended time (\( \lambda = 4.9 \)), you set \( k = 1 \):
  • \( P(X=1; \lambda=4.9) = \frac{e^{-4.9} \cdot (4.9)^1}{1!} \)
By calculating this, you acquire a probability figure which aids in risk assessment and planning. These calculated probabilities allow for evidence-based decisions in disaster preparedness and resource allocation during hurricane seasons.

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