What is next number in the pattern below:

131 517 192 123 ?

What does it mean?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

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

What is the centre of gravity?

Which alphabet letter is a question?

Through your logical capabilities, can you make 7 an even?

A maths symbol is hidden in the below Bar Graph. Can you decipher it?

What has many keys but can’t open a single lock?

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?