A letter is known to have come either from LONDON or CLIFTON. On the envelope just two consecutive letters are visible. What is the probability that the letter has come from

i. LONDON


ii. CLIFTON

Let us assume U1, U2 and A be the events as follows:


U1 = Letter comes from LONDON


U2 = Letter comes from CLIFTON


A = Event of getting two visible consecutive letters are ON


We know that letter comes from each place is most likely to occur. So, probability of getting letter will be same from each place.




Now,


P(A|U1) = P(visible two letters ON from london )




P(A|U2) = P(visible two letters ON from CLIFTON)




Now we find


P(U1|A) = P(The envelope comes from LONDON)


P(U2|A) = P(The envelope comes from CLIFTON)


Using Baye’s theorem:












The required probabilities are .


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