Interview Riddles

Interview riddles are famous questions asked during interviews by some big companies like Google, Microsoft, Intel etc.

Rickety Rope Bridge

Four people need to cross a rickety rope bridge to get back to their camp at night. Unfortunately, they only have one flashlight and it only has enough light left for seventeen minutes. The bridge is too dangerous to cross without a flashlight, and it’s only strong enough to support two people at any given time. Each of the campers walks at a different speed. One can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and the fourth takes 10 minutes to cross.

How do the campers cross the bridge in 17 minutes?

Riddle Answer

3 Switches and 1 Light Bulb

You have a set of 3 light switches outside a closed door. One of them controls the incandescent light bulb inside the room. With the door closed from outside the room, you can turn the light switches on or off as many times as you would like.

You can go into the room – one time only – to see the light. You cannot see whether the light is on or off from outside the room, nor can you change the light switches while inside the room.

No one else is in the room to help you. The room has no windows.

Based on the information above, how would you determine which of the three light switches controls the light inside the room?

Riddle Answer