A new factory machine which manufactures computer chips is malfunctioning and has a 20% defect rate. If 5 chips are randomly selected from the machine, find the following probibilities: non are defective; less than 2 are defective.

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- Feb 26th 2006, 08:38 AMbatman123Probability
A new factory machine which manufactures computer chips is malfunctioning and has a 20% defect rate. If 5 chips are randomly selected from the machine, find the following probibilities: non are defective; less than 2 are defective.

- Feb 26th 2006, 10:06 AMThePerfectHackerQuote:

Originally Posted by**batman123**

$\displaystyle \left(\frac{4}{5}\right)^5\approx .33$.

For the second part you need to use the formula:

$\displaystyle _nC_mp^m(1-p)^{n-m}$ to determine the probability of something exactly happening out of a certain amount of times.

Over here you need it to be zero times exactly OR one time exactly of getting a defect. Zero times is the same as all 5 where non-defective which is the same as in the first problem is 33%. To determine of getting exactly one defect use $\displaystyle _5C_1\left(\frac{4}{5}\right)^4\left(\frac{1}{5} \right)^{5-4}\approx .4$. Thus, the overall probability is the sum which is approximately 73%.

This is my 5:):)th post!! - Feb 26th 2006, 02:44 PMbatman123Thanks!
Thanks!!! for all your help :D

- Feb 27th 2006, 03:58 PMThePerfectHacker
Welcomed.