Stats problem. test tomorrow
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Stats problem. test tomorrow

[From: ] [author: ] [Date: 11-10-25] [Hit: ]
i have a test tomrorow.This fits a binomial, but with the small p value of .002,Let λ = np = 150(02) = 0.3 ,......
The probability that one 3 foot section of wire is defective is 0.002. If someone has 450 feet of wire then what is the probability they will have 3 or more 3 feet sections that are defective?

don't really know where to start, step by step would be awesome. i have a test tomrorow.

-
Jack -

This fits a binomial, but with the small p value of .002, the Poisson will be easier to calculate:

Let λ = np = 150(02) = 0.3 , [Note: the wire has 150 sections that equal 3 feet]

For Poisson, p(x) = (λ^x)(e^- λ) / x!

Now, to find the probability 3 or more 3 feet sections that are defective:

P(x >=3) = 1 - P(0) - P(1) - P(2) , are you with me? It is easier to solve this problem by looking at the complement.

P(0) = (0.3^0)(e^- 0.3) / 0! = 0.7408

P(1) = 0.2222

P(2) = 0.0333

P(x >=3) = 1 - P(0) - P(1) - P(2) = 1 - 0.7408 - 0.2222 - 0.0333 = 0.0037

Hope that helped

P.S. - if you would have used Binomial, the answer would be 0.0035
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