13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

It has horns but can’t beep. It is like to bleat but It is not a sheep. What is it?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different. How do you measure 45 minutes?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

Which is heavier: a ton of bricks or a ton of feathers?

What does this rebus photo means?

John was gifted a new Hayabusa. He drove x miles at 55mph. Then he drove x+20 miles at 40mps. He drove his bike for 100 minutes. How much distance did he travel?

I cry without having a voice.
I fly without having wings.
I bite without having teeth.
I whisper without a mouth.

Who am I?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?