Interview Puzzles Set 13 – Find The Murderer | Find The Murderer 2 | Find The Weights 2

Logic is the beginning of Wisdom not the end.

– Leonard Nimoy

Algorithmic thinking is really important as it enhances your thinking skills and can be nurtured with practice. (Refer the previous tutorial to know more about Algorithmic Thinking and try the puzzles before moving on to the solutions.)


 Solutions for the previous problems

Puzzle 12.1 Solution – Open Doors

Correct Answer:  10 doors

Explanation: All the doors which will be visited an even number of times will remain closed where as those doors which will be visited an odd number of times will be open. for ex. 2,3 have two factors(even) thus, they’ll be closed where as 1,4 have 1 and 3 factors(odd) thus, they’ll be open at the end.

If we analyze the numbers, we’ll get to know that all doors numbers which are perfect squares have an odd number of factors and thus, will remain open at the end. There are 10 perfect squares from 1-100 i.e 1, 4, 9, 16, 25, 36, 49, 64, 81, 100. Therefore, 10 doors will be open at the end and all other doors will be closed.


Puzzle 12.2 Solution – The Poisoned Wine

Correct Answer:  10 rats

Explanation: All the bottles are numbered from 1-1000, and all the rats are numbered from 1-10. Since the binary representation of each number contains not more than 10 bits, only 10 rats are needed. After converting the number to its binary form, the rats will be made to drink the wine based on the positioning of bit ‘1’. for ex. the number 31 after converting to its binary form is represented as 0 0 0 0 0 1 1 1 1 1, therefore the rats numbered 6,7,8,9 and 10 will be made to drink bottle numbered 31.

So at the end, we can find out all the rats that died(as bit 1) and which are alive( as bit 0) and find the bottle number from the binary number.


Solving these puzzles is fun, isn’t it? So, wear your logic caps and get ready for your next brain workout:

Algorithmic Thinking
Algorithmic Thinking

Quiz 13.1  – Find The Murderer

A man has been murdered and there are five suspects Sarah, Johny, Bruno, Jason and Amy.

A piece of paper was found near the dead body which had 7891011 written on it in blood.

Can you figure out who is the murderer? After all, it’s a matter of justice 😉    

Just think about it and post your answer in the comments. I’ll explain this in the next tutorial.

Solution Added – Solution of “Find the Murderer” puzzle


Quiz 13.2 – Find The Murderer 2

A rich man was murdered on a Sunday afternoon. Sherlock Holmes was called for the investigation. There were four suspects butler, cook, maid, gardener. Sherlock asked all the suspects, what they were doing at the time of the murder.

Butler: I was on leave.

Cook: I was cooking breakfast.

Maid: I was cleaning the house.

Gardener: I was watering the plants.

Based on their responses, Sherlock found out who the killer was. Can you figure out as well who the killer actually was?

Just think about it and post your answer in the comments.

Solution Added – Solution of “Find the Murdere 2” puzzle


Quiz 13.3  – Find the Weights 2

A king asks a wise man to visit his palace, to which the wise man responds:
“I will come some day in next month and will bring an object weighing from 1 kg to 40 kg. You have to tell me the exact weight using the balance and you can have only four other weighing blocks.

In preparation for the visit, the king wants your help. What are their weights?

Just think about the weights and their combinations and post your answer in the comments.

Solution Added – Solution of “Find the Weights 3” puzzle

So start thinking and comment answer to the questions asked above and wait for the next post for the solutions.

Do Share and Subscribe and comment your opinion, queries and suggestions.
Keep Learning. Happy Learning 🙂