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?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

2, 3, 5, 9, 17, _ What is the next number in the sequence?

It spends most of its day eating white, but when it’s quick enough, it gets to eat fruit and sometimes some blue things. It’s in a dark room, where the walls are blue, it runs from a ghost that roams the halls and haunts it all the time. What is it?

Alex is stranded on an island covered in forest.
One day, when the wind is blowing from the west, lightning strikes the west end of the island and sets fire to the forest. The fire is very violent, burning everything in its path, and without intervention the fire will burn the whole island, killing the man in the process.

There are cliffs around the island, so he cannot jump off.

How can the Alex survive the fire? (There are no buckets or any other means to put out the fire)

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

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

Can you find out who is the kidnapper in below Picture and why, Explain ?