#1 - River Riddle

Four people need to cross a dark river at night.They have only one torch and the river is too risky to cross without the tourch. if all people cross simultanoesly then torch light wont be sufficient.Speed of each person of crossing the river is different.cross time for each person is 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the river ?

The initial solution most people will think of is to use the fastest person as an usher to guide everyone across. How long would that take? 10 + 1 + 7 + 1 + 2 = 21 mins. Is that it? No. That would make this question too simple even as a warm up question.

Let's brainstorm a little further. To reduce the amount of time, we should find a way for 10 and 7 to go together. If they cross together, then we need one of them to come back to get the others. That would not be ideal. How do we get around that? Maybe we can have 1 waiting on the other side to bring the torch back. Ahaa, we are getting closer. The fastest way to get 1 across and be back is to use 2 to usher 1 across. So let's put all this together.

1 and 2 go cross
2 comes back
7 and 10 go across
1 comes back
1 and 2 go across (done)

Total time = 2 + 2 + 10 + 1 + 2 = 17 mins

#2 - Logic Escape Problem

In the kingdom of skull, King Norse did not allow any citizen to visit the world outside. Also only a person with a proper paperwork was allowed to enter or he was sent back. A wooden bridge was what connected the kingdom to the world. The king had appointed a sharpshooter who would check every five minutes on the bridge to check. After checking, he would go back to his hut and return exactly after five minutes again. The bridge took 9 minutes to cross.

A merchant was able to escape the kingdom without harming the shooter.

How ?

The merchant walked across the bridge for almost five minutes when the shooter was inside the bridge. Then he turned and started walking back to the kingdom of skull. On approaching the kingdom, he was asked of papers which he never had. Thus he was sent back.

#3 - Sherlock Holmes Murder Mystery Riddle

Sherlock breaks into a crime scene. The victim is the owner who is slumped dead on a chair and have a bullet hole in his head. A gun lies on the floor and a cassette recorder is found on the table. On pressing the play button, Sherlock hears the message 'I have committed sins in my life and now I offer my soul to the great Lord' and followed a gunshot Sherlock smiles and informed the police that's its a murder.

Why did he think so?

How can a dead person rewind back the tape himself?

#4 - Awesome Idea Puzzle Problem

Dwayne Johnson was running away with the loot from a heist in his car along with Vin Diesel. One tire was punctured and he dropped down to replace it. While changing the wheel, he dropped the four nuts that were holding the wheel and they fell into a drain. Vin Diesel gave him an idea using which they were able to drive till the rendezvous point.

What was the idea ?

Vin Diesel told him to use one nut from each of the other wheels.

#5 - Adobe Cool Logical Interview Puzzle

Suppose you are sitting in an interview and the interviewee asks you an aptitude question.

You have three buckets with capacity 4 liters, 8 liters and 10 liters and you have a large tank of water. Now you have to measure 3 liters of water precisely using those buckets. How will you do it?

It is impossible. The reason is that we are asked to measure 3 liters which is an odd number but the buckets we have can contain even liters of water only (4, 8 and 10). If you hoped to fill any of the bucket half, you will not be precise in measurement.

#6 - Popular Age Problem

Two old friends, Jack and Bill, meet after a long time.

Three kids
Jack: Hey, how are you, man?
Bill: Not bad, got married and I have three kids now.
Jack: That's awesome. How old are they?
Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.
Jack: Cool..But I still don't know.
Bill: My eldest kid just started taking piano lessons.
Jack: Oh, now I get it.

How old are Bill's kids?

3,3,8

Lets break it down. The product of their ages is 72. So what are the possible choices?

2, 2, 18 sum(2, 2, 18) = 22
2, 4, 9 sum(2, 4, 9) = 15
2, 6, 6 sum(2, 6, 6) = 14
2, 3, 12 sum(2, 3, 12) = 17
3, 4, 6 sum(3, 4, 6) = 13
3, 3, 8 sum(3, 3, 8 ) = 14
1, 8, 9 sum(1,8,9) = 18
1, 3, 24 sum(1, 3, 24) = 28
1, 4, 18 sum(1, 4, 18) = 23
1, 2, 36 sum(1, 2, 36) = 39
1, 6, 12 sum(1, 6, 12) = 19

The sum of their ages is the same as your birth date. That could be anything from 1 to 31 but the fact that Jack was unable to find out the ages, it means there are two or more combinations with the same sum. From the choices above, only two of them are possible now.

2, 6, 6 sum(2, 6, 6) = 14
3, 3, 8 sum(3, 3, 8 ) = 14

Since the eldest kid is taking piano lessons, we can eliminate combination 1 since there are two eldest ones. The answer is 3, 3 and 8.

#7 - Tricky Logical Puzzle

I have one of the three numbers: 1, 2 or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?

You will ask, I am thinking of a number from 2 and 3. Is the number I am thinking of smaller than or equal to the number you have in your mind?

Now, if I reply no, then the number is 1.
If I reply yes, then the number is 3.
If I reply don't know, then the number is 2.

#8 - IAS Logic Problem

Anabelle is a clever trader of rare artifacts. Each day she carries three boxes with each filled with thirty artifacts. The boxes cant hold more than that. She travels far of northern lands to sell these artifacts but on way, she comes across thirty checkpoints where she has to shed one of the artifact for each sack to the authorities for letting her pass.

How many artifacts will be left with her when she reaches her destination crossing all the check points ?

Anabelle is no dumb trader and she knows the strategy with the help of which she will be able to save 25 artifacts even after passing 30 check points.

All she will focus on is getting rid of the boxes as soon as possible.

To shed the first sack quickest possible, she will start filling artifacts from one box to other two. Assume that she is able to do that after passing through A check points.

(Space in first box) A + (Space in second box) A = (Remaining artifacts in third box) 30 -A
A = 10

Therefore, after 10 check points, she will be left with two boxes with 30 artifacts each. Now to get rid of the second box, she will start filling artifacts from second box to first box. Let us assume that she is able to get rid of the second box after B checkpoints.

(Space in first box) B = (Remaining artifacts in second box) 30 - B
B = 15

Therefore, after fifteen check points, she will be left with one sack with thirty artifacts in it.

Since she has five more check points left, she will have to give five more artifacts and after passing them all, she will still have 25 artifacts.

#9 - Oracle Probability Interview Question

What is the probability of choosing the correct answer at random from the options below.

a) 1/4
b) 1/2
c) 1
d) 1/4

If the answer is 1/4, then because 2 out of 4 answer choices are '1/4', the answer must actually be 1/2. This is a contradiction. So the answer cannot be 1/4.
If the answer is 1/2 (or 1), then because 1/2 (or 1) is 1 out of 4 answer choices, the answer must be 1/4. This is again a contradiction. So the answer cannot be 1/2 (nor 1).

So none of the provided answer choices are correct. Therefore the probability of choosing the correct answer is 0%

#10 - Logic Interview Question

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its color and put it back into the box, without seeing the color of the other ball.

How many such operations are necessary to correctly label the boxes?

Just One!

Because we know all labels are wrong.
So the BW box must be either BB or WW. Selecting one ball from BW will let you know which.
And the other two boxes can then be worked out logically.