Red ball,Black ball
There are two identical boxes namely box 1 and box 2. Box 1 has three red balls and one black ball. Box 2 has two black balls . One ball is randomly taken from box 1 and placed inside box 2 . After this one ball is taken from box 2 and is transferred to box 1 . After these two transfers a red ball is taken out. What is the probability that the red ball is taken out from box 1?