Difficulty ★★★★☆ Popularity ★★★★★

Outside a room there are three light switches. One of switch is connected to a light bulb inside the room.

Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb ??

Difficulty ★★★★★ Popularity ★★★★★

You are given a set of scales and 12 marbles. The scales are of the old balance variety. That is, a small dish hangs from each end of a rod that is balanced in the middle. The device enables you to conclude either that the contents of the dishes weigh the same or that the dish that falls lower has heavier contents than the other.

The 12 marbles appear to be identical. In fact, 11 of them are identical, and one is of a different weight. Your task is to identify the unusual marble and discard it. You are allowed to use the scales three times if you wish, but no more.

Note that the unusual marble may be heavier or lighter than the others. You are asked to both identify it and determine whether it is heavy or light.

Difficulty ★★☆☆☆ Popularity ★★★★★

You find yourself in a strange place guarded by two guards.One of the guard always say truth while other always lies.You don't know the identity of the two.You can ask only one question to go out from there. What should you ask?

Difficulty ★★★☆☆ Popularity ★★★★★

I have two rectangular wires.

Both of them have property that when i light the fire from one end , it will take 60 minutes to get completely burn.

However they do not burn at consistent speed (i.e it might be possible 1st 20% burn in 50 minutes and 80% can burn in 10 minutes).

So how could i measure 45 minutes ?

Difficulty ★★★☆☆ Popularity ★★★★★

I have two coins.

* One of the coin is a faulty coin having tail on both side of it.

* The other coin is a perfect coin (heads on side and tail on other).

I blind fold myself and pick a coin and put the coin on table. The face of coin towards the sky is tail.

What is the probability that other side is also tail ?

Difficulty ★★★★☆ Popularity ★★★★★

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....following a gunshot.

Sherlock smiles Of-course its a murder.

Why did he think so?

Difficulty ★★☆☆☆ Popularity ★★★★☆

Six jugs are in a row.

The first three are filled with coke, and the last three are empty.

By moving only one glass, can you arrange them so that the full and the empty glasses alternate?

Difficulty ★★★★☆ Popularity ★★★★☆

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

Difficulty ★★★☆☆ Popularity ★★★★☆

A newspaper is supposed to have 60 pages

but pages 24 and 41 are missing.

Which other pages won't be there?

Difficulty ★★★★☆ Popularity ★★★★☆

You are driving down the road in your car on a wild, stormy night, when you pass by a bus stop and you see three people waiting for the bus

An old lady who looks as if she is about to die.

An old friend who once saved your life.

The perfect partner you have been dreaming about.

Knowing that there can only be one passenger in your car, whom would you choose?