## poisson distribution problem

so flaws in metal produced by high temperatures occure at a rate of 1 per 10 square feet. what is the probability that there is 3 or more flaws in a 8 x 5 feet.

ok, so I know we need to use poisson disstribution on this, e^-np * np^k/k!.

howver, I dont know my np.

so 1 per 10 square feet means 1 per 10 x 10 feet....maybe we can say this is the same as .1 per 1 x 1 feet.

so how do I put this in terms of 8 x 5 feet?
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 8*5 = 40 square feet... you have 1 per 10 square feet.... that's means.... even a 10 years old kids can do this problem... what grade are you in? I don't realize middle school teachers start teaching poisson equation to the 7th grader.....

 Quote by vincentchan 8*5 = 40 square feet... you have 1 per 10 square feet.... that's means.... even a 10 years old kids can do this problem... what grade are you in? I don't realize middle school teachers start teaching poisson equation to the 7th grader.....