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September 26th, 2014, 05:44 AM   #1
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Confused

University purchases particular type of elec components.
60% from company A
40 % from company B

2% from A are faulty
1% from B are faulty

A) Draw tree diagram to represent the possible outcomes when a single component is selected at random.

B) what is prob that this component was supplied by company A and faulty?
C) calculate the prob that the component was defective?
D) Given that the compnent was defective, what is the prob that it was supplied by A?

Please help out.
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September 26th, 2014, 05:49 AM   #2
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i think tree diagram is

...............................^---->98% not
.......60%--->Company A ---> 2% faulty
0 ->
.......40% >--- Compant B---- 1% faulty
..................................^---->99% not

If people can follow that haha
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September 26th, 2014, 06:07 AM   #3
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i/ What is the probability that this component came from company A and is defective?

Probability supplied by A = 60% or 0.6
Probability defective if A = 2% or 0.02
Therefore;
0.6 x .02 = 0.012
So probability that this component came from company A = 0.6 (60%) and is defective = 0.012 (1.2%)

ii/ Calculate the probability the component was defective
I assume this incorporates both companies, so:
Company A = 0.6 (60%)
Company B = 0.4 (40%

As per question i/ 0.6 x 0.02 = 0.012 (1.2%)

Now for company B:
0.4 x 0.01 = 0.004 (0.4%)

Now add probability the component picked was defective = 0.012 + 0.004 = 0.016 (1.6%)

iii/ If was defective, what is probability it was supplied by company A?
Probability component from company A AND defective = 0.012 / 0.016 = 0.75 = 75% probability component was from company A and is then ALSO defective
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September 26th, 2014, 06:13 AM   #4
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That's right. Perfect answer!
Thanks from nathan

Last edited by v8archie; September 26th, 2014 at 06:15 AM.
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September 26th, 2014, 06:56 AM   #5
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Thanks.

thank you..
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