JEE Main 31-Aug-2021 Shift 1 Solved Paper

P (A) = Probability of first unit to function
P (B) = Probability of second unit to function
P(A)=0.9,P(A)=0.1
P(B)=0.8,P(B)=0.2
AB → Operate
AB→ Not operate
AB→ Not operate
AB→ Not operate
According to question, first failed and second functioning, given that instrument has failed, So according to Bayes theorem
∴P=

P(A).P(B)

P(A)P(B)+P(A)P(B)+P(A)P(B)

=

(0.1×0.8)

(0.9×0.2)+(0.1×0.8)+(0.1×0.2)

=

8

28

98P=

8

28

×98=28