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.
 

Who Did It?

Three of these statements are false, so who did it?

    Mr Red: “Mr Blue did it.”

    Mr Blue: “Mr Red did it.”

    Mr Green: “Mr Blue’s telling the truth.”

    Mr Yellow: “Mr Green’s not lying.”

Find who did it!

Mr. Blue Did it!

What were the statements by suspects?

If Mr. Yellow is telling the truth then Mr. Green and hence Mr. Blue all are telling the truth. This is against the given data.

This hold true if we assume that Mr. Green is telling the truth or Mr. Blue telling the truth. In all cases, 3 statements would be true.

Hence, only statement of Mr.Red is true and that's why Mr. Blue did it!

 

The Mongolian Postal Service

The Mongolian Postal Service has a strict rule stating that items sent through the post must not be more than 1 meter long. Longer items must be sent by private carriers, and they are notorious for their expense, inefficiency, and high rate of loss of goods.

Boris was desperate to send his valuable and ancient flute safely through the post. Unfortunately, it was 1.4 meters long and could not be disassembled as it was one long hollow piece of ebony. Eventually he hit on a way to send it through the Mongolian Postal Service. 

What did Boris do?

That's what needed for safe delivery! 

Deliverying The Valuable Safely!

What was the problem in delivery?

Boris keeps the flute diagonally in a square shaped suitcase whose side measuring 1m.

Since side is 1 m the diagonal of such suitcase must be square root of 2 i.e. 1.414 m. So the 1 m long flute can easily fit diagonally in such suitcase.

 

Earnings Of People

Twenty men, women and children earn twenty coins between them. Each man earns 3 coins, each woman 1.5 coins and each child 0.5 coin.

How many men, women and children are there?

Find number of each of them here!

Number Of Earning People

What was the question? 

Let's suppose there are m men, w women and c children.

As per given data,

m + w + c = 20   ......(1)

3m + 1.5w + 0.5c = 20   .....(2)

Multiply equation (1) by 3 and then subtracting from (2), we get,

5m + 2w = 20.

For m and w to be whole numbers, m must be 2 and w must be 5 satisfying above equation.

Hence, from (1),

c = 20 - 2 - 5 = 13.

 
To conclude, there are 2 men, 5 women and 13 children.

Draining Reservoir

A large fresh water reservoir has two types of drainage system: small pipes and large pipes.

6 large pipes, on their own, can drain the reservoir in 12 hours.

3 large pipes and 9 small pipes, at the same time, can drain the reservoir in 8 hours.

How long will 5 small pipes, on their own, take to drain the reservoir?

Find here the exact time required! 

Time To Drain The Reservoir

Here is the question! 

Let T be the capacity of the tank. Let L be the large pipe and S be the small pipe.

T/6L = 12

L = T/72

T/(3L + 9S) = 8

Putting L = T/72,

S = T/108

Hence T/5S = 108/5 gives S = 21.6 hours.

To conclude, small pipes require 21.6 hours i.e. 21 hours and 36 minutes to drain the reservoir.

Journey In Parts

Someone drove from Aardvark to Beeville.

On the first, day they traveled 1/3 of the distance.

On day two, they traveled 1/2 of the remaining distance.

On day three, they traveled 2/3 of the remaining distance.

On day four, after covering 3/4 of the remaining distance, they were still 5 miles away from Beeville.

How many miles had they covered so far?

Know the total distance traveled!
 

Total Distance In The Journey

Click for the question! 

We need to start in reverse.

In last part after covering 3/4 still 5 miles left which accounts for 1/4 of remaining distance. Hence, 20 miles were left at the start of DAY 4.

On DAY 3, 2/3rd covered leaving 20 miles for DAY 4. That means 20 miles distance is remaining 1/3rd. Hence, at the start of DAY 3, 60 miles were left.

On DAY 2, 1/2 of covered leaving 60 miles for DAY 2. So that means 60 miles distance is remaining 1/2. So at the start of DAY 2, 120 miles yet to be covered.

On DAY 1, 1/3 of covered leaving 120 miles for DAY 2. Meaning 120 miles distance is remaining 2/3. Hence, 180 miles yet to be covered at the start of DAY 1.

Out of 180 miles, 175 covered in 4 days still 5 miles left.

Find The Parking Floor

Six people park their car in an underground parking of a store. 

The store has six floors in all. Each one of them goes to different floor.

Simon stays in the lift for the longest.

Sia gets out before Peter but after Tracy.

The first one to get out is Harold.

Debra leaves after Tracy who gets out at the third floor.

Can you find out who leaves the lift at which floor? 

 
Was it really so difficult? 

Finding The Parking Floor

What was the given data? 

The sentence 'The first one to get out is Harold.' suggests that the Harold leaves the lift at the 1st floor.

Similarly, the sentence - 'Simon stays in the lift for the longest.' suggests that Simon leaves he lift at the 6th floor.

Next, sentence - 'Debra leaves after Tracy who gets out at the third floor' suggests Debra leaves the lift at the 3rd floor.

Clearly, the sentence - 'Sia gets out before Peter but after Tracy.' suggests that Sia leaves the lift at the 4th floor.

Also, it is clear that Debra leaves the lift at the 2nd floor and Peter at the 5th floor.

Summary -

Harold leaves at the first floor.

Debra leaves at the second floor.

Tracy leaves at the third floor.

Sia leaves at the fourth floor.

Peter leaves at the fifth floor.

Simon leaves at the sixth floor.

The Lossless Mistake

Bob buys two things in a shop. With his pocket calculator he calculates in advance what he has to pay: 5.25 dollars. But what he does not notice is that he pressed the division instead of the addition button. At the desk he is not surprised if he hears that he has to pay 5.25 dollars. 

What is the price of the two things Bob has bought?

Know the cost of those 2 things.

For Mistake To Be Lossless...

What was the mistake?

Let's assume that those things costs a and b respectively.

As per Bob's wrong calculation,

a / b = 5.25

a = 5.25 b  ..........(1)

And according to what should have been correct,

a + b = 5.25

Putting (1) in above,

5.25b + b  = 5.25

6.25b = 5.25

b = 0.84

Again putting this value in (1) gives,

a + 0.84 = 5.25

a = 5.25 - 0.84

a = 4.41

 
Hence the cost of 2 things are $4.41 and $0.84.

The Game Of Guesses

In a contest, four fruits (an apple, a banana, an orange, and a pear) have been placed in four closed boxes (one fruit per box). People may guess which fruit is in which box. 123 people participate in the contest. When the boxes are opened, it turns out that 43 people have guessed none of the fruits correctly, 39 people have guessed one fruit correctly, and 31 people have guessed two fruits correctly.

How many people have guessed three fruits correctly, and how many people have guessed four fruits correctly?

Escape to answer without getting tricked! 

Correct Guesses From The Game Of Guesses

What was the game?

There is absolutely no way that somebody has guessed 3 correctly since if 3 are correct then 4th has to be correct. Hence, nobody guessed 3 correctly.

So number of people with all 4 guess correct is equal to 123 - 43 - 39 - 31 = 10.

10 people guessed all the 4 fruits correctly.