What always comes into a house through the keyhole?

You can hear me, but you can't touch or see me.

What am I?

If all Goats are Sheep and all Sheep are Deers, are all Deers Goats ?

In Greek mythology, the Sphinx sat outside of Thebes and asked this riddle of all travellers who passed by. If the traveller failed to solve the riddle, then the Sphinx killed him/her. And if the traveller answered the riddle correctly, then the Sphinx would destroy herself. The riddle:

What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?

Oedipus solved the riddle, and the Sphinx destroyed herself.

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?

Imagine you are in a room with no windows or doors. How will you get out?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

There are three Athletes (John, Tarun and Harish) and their individual Coaches (Jacob, Meenaxi and Priyanka) standing on the shore.
No Coach trusts their Athlete to be near any other Coach unless they are also with them.
There is a boat that can hold a maximum of two persons.
How can the six people get across the river?

How do you go from 98 to 720 using just one letter?