
Financial Risk Manager Part 1
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If the rate at which accidents occur in a U.S. city is, on average, three every day, calculate the probability that more than 5 accidents occur on a single day.
Explanation:
Explanation
This problem involves a Poisson distribution where the average rate of accidents is λ = 3 per day.
Poisson Probability Formula:
[P(N = n) = \frac{e^{-\lambda} \lambda^n}{n!}]
Step-by-step calculation:
We need to find P(N > 5), which equals: [P(N > 5) = 1 - P(N \leq 5)] [P(N > 5) = 1 - [P(N = 0) + P(N = 1) + P(N = 2) + P(N = 3) + P(N = 4) + P(N = 5)]]
Individual probabilities:
- P(N = 0) = [\frac{e^{-3}3^0}{0!} = e^{-3} = 0.0498]
- P(N = 1) = [\frac{e^{-3}3^1}{1!} = 3e^{-3} = 0.1494]
- P(N = 2) = [\frac{e^{-3}3^2}{2!} = \frac{9e^{-3}}{2} = 0.2240]
- P(N = 3) = [\frac{e^{-3}3^3}{3!} = \frac{27e^{-3}}{6} = 0.2240]
- P(N = 4) = [\frac{e^{-3}3^4}{4!} = \frac{81e^{-3}}{24} = 0.1680]
- P(N = 5) = [\frac{e^{-3}3^5}{5!} = \frac{243e^{-3}}{120} = 0.1008]
Sum of probabilities: [P(N \leq 5) = 0.0498 + 0.1494 + 0.2240 + 0.2240 + 0.1680 + 0.1008 = 0.9160]
Final probability: [P(N > 5) = 1 - 0.9160 = 0.0840]
Therefore, the probability that more than 5 accidents occur on a single day is 0.084.