What is the probability that a state will get hit by a major tornando at least once in the next 10 years if the probability of getting hit in one year is 1/10?

Question

anonymous · Answer

poisson distribution for this one 
$$\lambda=0.1$$

anonymous · Answer

and "at least once" means "not none" so caclulate the probability of no tornadoes and subtract the result from one

anonymous · Answer

actually i think it is easier than that.  since you are using a ten year period and the probability is 1/10 for one year, you can use 
$$\lambda =1$$

anonymous · Answer

$$P(x=0)=e^{-\lambda}=e^{-1}$$

anonymous · Answer

does this look familiar or are you supposed to do it a different way?

anonymous · Answer

i think your answer is 
$$1-e^{-1}$$

anonymous · Answer

I think a different way but I'm not sure...sorry

anonymous · Answer

are you using the poisson distribution?  i am not sure how else you could do this one

anonymous · Answer

i guess you could say they are independent, so probability of no tornadoes in any one years is 
$$\frac{9}{10}$$ so no tornadoes 10 years in a row is 
$$(\frac{9}{10})^{10}$$ so "at least one" in ten years is 
$$1-(\frac{9}{10})^{10}$$ that might work better

anonymous · Answer

using that method i get 0.65 as your probability

anonymous · Answer

yeah that definitely looks more like what im doing haha

anonymous · Answer

Thank you very much!

anonymous · Answer

poisson gives 0.63 but that is more of an approximation, so stick with that one