Probability Question 201
Question: Abhay speaks the truth only 60%. Hasan rolls a die blindfolded and asks abhay to tell him if the outcome is a prime abhay says, YES what is the probability that he outcome is really prime?
Options:
A) 0.5
B) 0.75
C) 0.6
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
There are two cases when Abhay will say Yes.
Case (i) the number that come out is a prime and abhay is speaking truth, probability for this case is $ P(P)\times P(T) $
Here P (P) = Probability of getting a prime = 3/6 = ½ = 0.5 P (T) is probability that Abhay is speaking truth and P (T) = 0.6
So probability for this case is $ 0.5\times 0.6=0.3 $ .
Case (ii) The number that come out is not a prime and Abhay is not speaking truth, probability for this case is $ P(P’)\times P(T’)=0.5\times 0.4=0.2 $
So total probability for the given case is 0.3+0.2=0.5.
New sample space is 0.5 and we have to find the probability of case (i) which is 0.3/0.5=0.6.
BETA
