poisson distribution problem

semidevil

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?

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.....

semidevil

haha...whoops, wasn't thinking about this...I got it...haha