rahulranjan86
New member
- Joined
- Feb 18, 2012
- Messages
- 9
Two shipments of machine parts are recieved. The first shipment contains 1000 parts with 10% defects and the second shipment contains 2000 parts with 5% defects. One shipment is selected at random. Two machine parts and tested and found good. Find the probability that the tested parts were selected from first shipment.
My Attempt:
Probability of selecting a shipment.
P(S) = 0.5
Probability of a part being defective when from shipment 1
P(D|1) = 0.1
Probability of a part being defective when from shipment 2
P(D|2) = 0.05
P(D) = P(D|1).P(1) + P(D|2).P(2)
P(D) = 0.075
then probability of part not being defective.
P(D') = 1 - 0.075 = 0.925
P(1|D') = P(1 and D') / P(D')
= 0.5*0.925 / 0.925
= 0.5
I have tried the above solution to the problem. I am not sure if this is correct. Please let me know if I am going wrong and how do I approach for a correct answer.
My Attempt:
Probability of selecting a shipment.
P(S) = 0.5
Probability of a part being defective when from shipment 1
P(D|1) = 0.1
Probability of a part being defective when from shipment 2
P(D|2) = 0.05
P(D) = P(D|1).P(1) + P(D|2).P(2)
P(D) = 0.075
then probability of part not being defective.
P(D') = 1 - 0.075 = 0.925
P(1|D') = P(1 and D') / P(D')
= 0.5*0.925 / 0.925
= 0.5
I have tried the above solution to the problem. I am not sure if this is correct. Please let me know if I am going wrong and how do I approach for a correct answer.