Answer:
Option C
Explanation:
Let x=P (computer turns out to be defective, given that it is produced in plant T2)
⇒ x=P(DT2) .............(i)
where , D= Defective computer
∴ P (computer turns out to be defective given that is produced in plant T1)=10x
i.e, P(DT1)=10x .......(ii)
Also, P(T1)=20100 and P(T2)=80100
Given, P (defective computer )= 7100
Using law of total probability,
P(D)=9(T1).P(DT1)+P(T2).P(DT2)
∴ 7100=(20100).10x+(80100).x
⇒ 7= (280)x
⇒ x=140 ..........(iii)
∴ P(DT2)=140 and P(DT1)=1040
⇒ P(¯DT2)=1−140=3940
and P(¯DT1)=1−1040=3040 .........(iv)
Using Baye's theorem,
P(T2D)=P(T2∩¯D)P(T1∩¯D)+P(T2∩¯D)
=P(T2).P(¯DT2)P(T1).P(¯DT1)+P(T2).P(¯DT2)
=80100.394020100.3040+80100.3940=7893