Probability

Question

In a b olt factory 30%, 50% and 20% of pro duction is done on machine s I, I I and I I I
resp ectively. It is known that 4%, 3% and 5% of the output of these resp ective machines
is defective.
(a) What is the probability that a randomly selected bolt is defective?
(b) What is the probability that a defective bolt had been manufactured by machine
I I I?
(c) What is the probability that a randomly selected bold is not defective and has been
produced by machine I?

Answer 1

For part (a) you can use this formula: P(D) = P(D|A)P(A) + P(D|B)P(B) + P(D|C)P(C)

 

For (b) and (c) use Bayes' Theorem.

 

 

Claire,

 

I see you have posted a lot of probability and statistics questions. I would recommend you sign up for a tutoring session  with one of the tutors here (preferably me) so you can be shown step by step how to do these questions.

 

Arnold