question

there are three coins. one is a coin having tails on both faces, another is a biased coin that comes up tails  70% of the time and the third is an unbiased coin. one of the coins is chosen at random and tossed, it shows tail. find the probability that it was a coin with tail on both the faces.

 

 

 

 

 

 

 

 

let e: the coin shows tail
also let: the related coin is having tails on both the faces, a baised coin & un baised coin respectively.
here
 
by baye's theorem