How do you place 50 good candies and 50 rotten candies in two boxes such that if you choose a box at random and take out a candy at random, it better be good! Hint
That means probability of choosing a good candy should be highest.
Placing all bad in 1 box and all good in another will give probability of choosing good just half. But placing only one type of candy in one box makes sure that good candy has a probability of at-least 1/2
Put 1 good candy in one box and all other (49 good and 50 rotten candies) in second box
Put 1 good candy in one box and all other (49 good and 50 rotten candies) in second box. This will give a probability of (1/2)*1 + (1/2)*(49/100) = 74.5%