Rat and Poisonous Milk Bottles | Puzzles for Interview - Interview Preparation PDF Download

Introduction:
Imagine you have four bottles of milk, but one of them is poisonous. You cannot tell which one is poisonous by just looking at them. However, you have a rat that dies exactly after 10 hours of drinking the poisoned bottle. You also have a clock that measures time only in hours. How can you identify the poisonous bottle within 24 hours?

Solution

To identify the poisonous bottle, you need to feed the rat with milk from each bottle. But you cannot feed the rat all four bottles at once. Instead, you need to feed the rat one bottle at a time, starting from the first bottle.

• Step 1: At the start of the first hour, feed the rat with milk from the first bottle.
• Step 2: At the beginning of the second hour, feed the rat with milk from the second bottle.
• Step 3: Similarly, at the start of the third hour, feed the rat with milk from the third bottle.
• Step 4: Now, wait for the rat to die. If the rat dies exactly after 10 hours of drinking the milk, the first bottle is poisonous.
• Step 5: However, if the rat dies after 11 hours of drinking the milk, the second bottle contains poison.
• Step 6: If the rat dies after 12 hours of drinking the milk, the third bottle is the poisonous one.

Conclusion

By following this strategy, you can identify the poisonous bottle within 12 hours. Therefore, you have another 12 hours to take necessary precautions and prevent anyone from drinking the poisonous milk.