Why Wine Glass Stem is so long?

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?

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?

Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

A sundial has the fewest moving parts of any timepiece. Which has the most?

Why is it against the law for a man living in Delhi to be buried in Mumbai?

Identify the 10 differences between the two given pictures.

Can you place three balls such that the equation shown in the picture holds true?