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.

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?

What can you see in the middle of March and April that you can never see in any other month?

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

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

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

Can you count the number of triangles in the given picture?

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?

What demands an answer, but asks no questions

Replace the 'X' with any mathematical symbol to make the expression equal to 111.

18 X 12 X 2 X 3 = 111