Question

A manufacturer of calculators buys integrated circuits from supplies A,B and C. Fifty percents of the circuits come from A, 30% from B and 20% from C. One percent of the circuits supplied by A have been defective, 3% of Bs have been defective and 4% of C has been defective in the past.

(a) Suppose that a circuit is randomly selected. What is the probability that it is defective
(b) A circuit is selected at random and found to be defective. What is the probability it was manufactured by A?

Answer 1

0.022 and 0.2273

Explanation:

Given that a manufacturer of calculators buys integrated circuits from supplies A,B and C.

Supplies A B C Total

Circuits 0.5 0.3 0.2 1

Defective 0.01 0.03 0.04

P(defective) 0.5*0.01+0.3*0.03+0.2*0.04

0.022

So probability for defective = 0.022

b) Prob ( circuit selected is from A/circuit defective)

=
`(0.5*0.01)/(0.022) \\=0.2273`