Andaz Apna Apna Andaz Apna Apna

This is what happens when math nerds watch "Andaz Apna Apna" movie. They find a problem! Remember that scene where Robert and Bhalla try to poison Raveena, but then the drinks get mixed up?

In a quick recap, there's one poisoned drink, five regular drinks and six people: Amar, Prem, Raveena, Karishma, Bhalla, and Robert.

The first four have their drinks and don't die. At this point, Bhalla and Robert have to have their drinks, and one of them is poisoned. Bhalla decides to swap his drink with Robert.

Now, thinking back, this is essentially the Monty Hall problem with the doors and the goat, except in this case, it's the reverse - you obviously don't want the poisoned glass.

When the drinks were first distributed, Bhalla had a 1/6 chance of having a poisoned glass. By the time Amar, Prem, Raveena, and Karishma had theirs, now there were only two glasses left, one which was poisoned.

By switching glasses, Bhalla increased his chances of getting the poisoned drink from 1/6 to 5/6. Which was, of course, the wrong decision. It would have been more advantageous to stay with his original drink.