Suppose we have four boxes A, B, C and D containing coloured marbles as given below:


Box



Marble colour




Red



White



Black



A



1



6



3



B



6



2



2



C



8



1



1



D



0



6



4



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 A?, box B?, box C?

Let us assume R be the event of drawing the red marbles

Let us also assume EA, EB andEC denote the boxes A, B and C respectively


It is given in the question that,


Total number of marbles = 40


Also, total number of red marbles = 15


∴



Probability of taking out the red marble from box A,




Also, probability of taking out the red marble from box B,




And, Probability of taking out the red marble from box C,




12