Q. 12. Suppose we have four boxes A,B,C and D containing coloured marbles as given below:
One of the boxes has been selected at random and a single marble is drawn from it. If the marble is red, what is the probability that it was drawn from box B?
Let R be event of drawing red marble.
Let respectivly denote event of selecting box A,B,C.
Total marbles = 40
Red marbles =15
Probability of drawing red marble from box B is