Can you identify if it's a murder or a suicide ?

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

Count the number of lines in the image below ?

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

A boy was at a carnival and went to a booth where a man said to the boy, "If I write your exact weight on this piece of paper then you have to give me $50, but if I cannot, I will pay you $50." The boy looked around and saw no scale so he agrees, thinking no matter what the carny writes he'll just say he weighs more or less. In the end the boy ended up paying the man $50. How did the man win the bet?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?