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# Statistics question HELP!:'( Watch

1. Hey guys a little help on this question.
Ahhh statistics is the devil :'(

At a factory that makes crockery the quality control department has found that 10% of plates have minor faults.These are classed as 'seconds' .Plates are stored in batches of 12.The number of seconds in a batch is donoted by X.

i) State an appropriate distribution with whhich to model X.Give the value(s) of any parameters(s) and state any assumptions required for the model to be valid.

Assume now that your model is valid.

ii) Find
a)P(X=3)

b)P(X > 1)

iii) A random sample of 4 batches is selected.Find the probability that the number of these batches that contain at least 1 second is fewer than 3.

thanks
2. Which distributions do you know about?

As for assumptions to make, could you make a distribution for this if there were 2 seconds out of 20 plates in total? What needs to be true if the 10% figure is to stay (roughly) the same if we account for some of the seconds?
3. (Original post by chelley2)
Hey guys a little help on this question.
Convince yourself that X follows a binomial distribution and find the values of n and p. This is essential to the question and if you can't convince yourself of this then you will struggle immensely to complete it.

Of course, I could tell you like the previous poster to think about what distributions you know, but with questions like this it's easier for you to understand if I tell you the distribution you require and you work out why.

I hope this helps.

Darren
4. I know the binomial and geometric distributions .
Would I use the binomial because the number of trials is fixed?
It would be X~B(12,p).is p 0.1?
I think I get it now after re-reading my notes
Thank you guys

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