You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

Rose, Lily and Jasmine decided to buy flowers for their moms on Mother's Day. One of them bought lilies, the other roses, and the third one jasmines.
'It's funny!' said the girl with roses, 'we bought roses, jasmines and lilies, but none of us bought the flowers matching her name'.
'You're right!', said Lily.
What kind of flowers did each of the girls buy?

What always comes into a house through the keyhole?

Solve the equation in the image by looking at the pattern closely.

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

In the attached figure, you can see a chessboard and two rooks placed on the chess board. What you have to find is the number of squares that do not contain the rooks. How many are there?

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.

A word I know has six letters it contains, remove one letter and 12 remain. What is it?

What work can one never finish?

Solve the following series:
AZ, GT, MN, __, YB