what's the probability of getting a king or a queen from a pack of 52 cards?

You are given 16 witch hats. The hats are divided in four different colours – red, blue, green and yellow. Every colour has been assigned to four hats. Now each of the hat will be glued with a label of an arithmetic sign – ‘+’, ‘-‘, ‘x’ or ‘/’. But you can label one sign only once on one colour. In such an arrangement, the hats can be uniquely defined by its colour and symbol.

Can you arrange all the 16 hats in a 4x4 grid in a fashion that no two rows and columns have a repetition of colour or sign?
We have arranged four hats in the below picture to assist you.

Why do we preferably have round manhole covers and not square ones?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

Can it be possible to build a house that has all its four walls facing towards the South?

What four weights can be used to balance from 1 to 30 pounds?

A Child was born in Lahore, Pakistan. Still, the child is not a Pakistani citizen. why?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?