Who Stole The Money?

A man placed a $100 dollar bill on his desk and left for work. When he returned back the money was gone. He has three suspects: the cook, the maid and the electrician.

The cook said he put the bill under a book on his desk to keep it safe. The man checked and it is no longer there.

The maid said she moved the bill to the inside of the book between page 1 and 2 while she was cleaning. Again, the man checked the book and there was nothing between page 1 and 2.

The electrician said he saw the bill sticking out of the book and he moved it between page 2 and 3 to keep it safe.

Who stole the money?

Know who is the thief? 

The Electrician Stole The Money

Who were other suspects?

The electrician must be lying. Since the man checked between page 1 and 2 the next pair of page must be 3 and 4 not 2 and 3. The page numbers 2 and 3 must be the part of single page. 

So how can electrician move it between page 2 and 3? 

The Dog Of The Commander

A long and straight row of soldiers is marching with constant speed. The dog of the commander runs along the row from the end till the beginning, from the beginning till the end, from the end till the beginning etc. This takes always 2 minutes, 1 minute, 2 minutes, etc. 

At some point the soldiers have to pass a very small bridge. However, the commander does not trust the strength bridge completely. He wonders how much time it will take them to pass the bridge when they stay marching with the same speed. 

How much time is that?  

You can skip to the answer! 

Passing A Very Small Bridge

What is the question?

For march of soldiers to pass any point, there must be first man crossing that point first and then later the last man should cross the same point. 

Now the dog runs from the first to last man in 1 minute, then runs back to first man in 2 minutes and again back to last man in 1 minutes. That means the dog must be at the same point where he started journey from first man. In other words, the dog has run for 2 minutes in both the directions. Hence, he must be at the same point after 4 minutes.

Interestingly, the dog was at first man when started & after 4 minutes ended at the last man of the march. Since dog is at the same point after 4 minutes, the entire march of soldiers is crossed that point in 4 minutes as first and last man have crossed that point.

The same when applied to a very small bridge which can be assumed as a point, we can say that it requires 4 minutes for soldiers to cross it.