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September 26th, 2014, 05:44 AM  #1 
Member Joined: Aug 2014 From: scotland Posts: 45 Thanks: 0  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. 
September 26th, 2014, 05:49 AM  #2 
Member Joined: Aug 2014 From: scotland Posts: 45 Thanks: 0 
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 
September 26th, 2014, 06:07 AM  #3 
Member Joined: Aug 2014 From: scotland Posts: 45 Thanks: 0 
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 
September 26th, 2014, 06:13 AM  #4 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,330 Thanks: 2455 Math Focus: Mainly analysis and algebra 
That's right. Perfect answer!
Last edited by v8archie; September 26th, 2014 at 06:15 AM. 
September 26th, 2014, 06:56 AM  #5 
Member Joined: Aug 2014 From: scotland Posts: 45 Thanks: 0  Thanks.
thank you..


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