An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

What can you hold in your right hand, but never in your left hand?

You walk into a room where there are three primates held in their respective cages:
1) A lion who is eating the flesh of a goat.
2) An orangutan who is playing with blocks.
3) A donkey who is sitting idle.

Who is the most intelligent primate in the room?

Prove that twice of ten is the same as twice of eleven.

Christina, Allison and Lena are 3 daughters of John a well-known Mathematician, When I asked John the age of their daughters. He replied "The current age of her daughters is prime. Also, the difference between their ages is also prime."

How old are the daughters?

Andrew’s doctor gives him three pills and tells him to take one every half hour. How much time will have passed by the time Andrew’s taken all three pills?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

What kind of band never plays music?

There are forty elephants and they have forty-fore heads. How can this be possible?