Consider an urn in which 4 balls have been placed by the following a fair coin is tosed,if the coin falls ahead,a white ball is placed in the turn,and if the coin falls tail,a red ball is placed in urn, what is the probability of that urn will contain 3 balls

Dear Student

Your question is wrong as there are already 4 balls in the urn and you are placing mor eno. of balls whether head comes or tail comes . So, definately the no. of balls would be greater than 4 .
you have given the wrong question, kindly provide correct question so that we can assist you

Thanks