If eleven plus two equals one, what does nine plus five equal?

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?

Which word is least like the others? Third, fourth, fifth, sixth, seventh, eighth, ninth?

Do you know of a place where the wind blows south and then suddenly shifts direction towards the north?

Decode the movie name from the below picture?

What breaks yet never falls, and what falls yet never breaks?

What kind of band never plays music?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?