15.6.19 Definition and properties of probability

Problem: There are 8 balls in the \( 1^{\text {st }} \) box, 2 of them are white, and in the \( 2^{\text {nd }} \) box there are 12 balls, 7 of which are white. 1 ball has been randomly taken out of the \( 1^{\text {st }} \) box and put into the \( 2^{\text {nd }} \) one. Find the probability that the ball, taken out of the \( 2^{\text {nd }} \) box after that, will turn out to be white.