I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

There are 3 apples in the basket and you take away 2. How many apples do you have now?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

Rahul decided to meet Simran so he boards a local train from Bombay station. Just after the station, there is a 1km long tunnel. The train starts and is now accelerating. Rahul is a claustrophobic guy, so what is the best position for him to sit?

Find the next number in the series.
1 10 24 43 67 ?

A girl was sitting in her hotel room when she heard a knock on the door. She opened the door and found that a man was standing outside. The man said, "Oh! I am really sorry, I thought this was my room." He then walked through the corridor to the elevator. The girl did not know the man. She closed her door and called security asking them to apprehend the man. What made her suspicious of that man? He might have been genuinely mistaken.