I’m tall when I’m young, and I’m short when I’m old. What am I?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

A large water tank has two inlet pipes (a large one and a small one) and one outlet pipe. It takes 3 hours to fill the tank with the large inlet pipe. On the other hand, it takes 6 hours to fill the tank with the small inlet pipe. The outlet pipe allows the full tank to be emptied in 9 hours.

What fraction of the tank (initially empty) will be filled in 0.64 hours if all three pipes are in operation? Give your answer to two decimal places (e.g., 0.25, 0.5, or 0.75).

John was driving a bus and got stuck when passing through an underpass. Then came Jacob with a needle and got the bus out of the underpass.

What did the boy do?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat

Why is it very easy to weigh a fish?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Can you count the number of triangles inside a triangle?

Solve the equation by replacing the alphabet with numbers.

MOM + MOM + NO = BOOK=

Forwards I am heavy, backward I am not. What am I?