There are two boxes, one containing 10 red balls and the other containing 10 green balls. You are allowed to move the balls between the boxes so that when you choose a box at random and a ball at random from the chosen box, the probability of getting a red ball is maximized. This maximum probability is Pick one.
A) 14/19  B) 14/18  C) 14/11  D) 14/13  E) 14/15
If rearrangement is not allowed, then actual probability of picking up a red ball = 12(10)+12(0)=1212(10)+12(0)=12   As we are allowed to move the balls, we keep only 1 red in the first box, and shirt the remaining 9 to the second.   So = 12×(1)+12×91/9=14/19
<result>A</result>
There are two boxes, one containing 10 red balls and the other containing 10 green balls. You are allowed to move the balls between the boxes so that when you choose a box at random and a ball at random from the chosen box, the probability of getting a red ball is maximized. This maximum probability is