If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

I look at you, you look at me I raise my right, you raise your left. What am I?

If one and a half boys, eat one and a half burgers in one and a half hours.

How many burgers can 9 boys eat in 3 hours?

What is so fragile that saying its name breaks it?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

What is at the end of a rainbow?

A convention is held where all the big logicians are summoned. The master places a band on everyone's forehead. Now all of them can see others bands but can't see his own. Then they are told that there are different colours of bands. All the logicians sit in circle and they are further explained that a bell will ring at regular intervals. The moment when a logician knew the colour of band on his forehead, he will leave at the next bell. If anyone leaves at the wrong bell, he will be disqualified.

The master assures the logicians that the puzzle will not be impossible for anyone of them. How will the logicians manage ?

What am I?