Solution:

Swim Underwater

Solution:

I am a windmill.

Solution:

I am Voice

Solution:

8

Solution:

Ms. Britney did it.

We will take up every person and analyze the statements over all of them one by one.

Case 1: Ms. Britney did it, then
Statement 1 => true
Statement 2 => false (as Rihanna did not do it)
Statement 3 => false (as Ms. Britney is lying)
Statement 4 => false (as Ms. Gwyneth is lying)
Our first guess itself was right but let us confirm our analysis by analyzing the statements over others.

Case 2: Ms. Rihanna did it, then
Statement 1 => false (as Ms. Britney did not do it)
Statement 2 => true
Statement 3 => true (as Ms. Britney is not lying)
As per the conditions, three statements had to be wrong but here, we have two statements right which clearly contradict the condition.

Case 3: Ms. Gwyneth did it, then
Statement 1 => false (as Ms. Britney did not do it)
Statement 2 => false (as Ms. Rihanna did not do it)
Statement 3 => false (as Ms. Britney is lying)
Statement 4 => false (as Ms. Gwyneth is lying)
She did not do it as all the statements are false.

Case 4: Ms. Yoon did it, then
Statement 1 => false (as Ms. Britney did not do it)
Statement 2 => false (as Ms. Rihanna did not do it)
Statement 3 => false (as Ms. Britney is lying)
Statement 4 => false (as Ms. Gwyneth is lying)
All four statements are false in her case as well thus she did not do it.

Therefore we have proved that Ms. Britney did it.

Solution:

40 triangles

16 + (8x2) + (4x2) + (1x2) + (1x2)

Solution:

Just add G before the number ONE and it will be GONE.

Solution:

20 Triangles

Explanation:
Let us consider the smallest side of the triangle as 1 cm.
Now count and you will find out that we have 1 + 5 + 5 + 1 = 12 triangles with the side 1 cm.
Number of triangles with side 2 cm = 1 + 2 (triangles facing upwards) + 1 + 2 (triangles facing downwards = 6 triangles
Number of triangles with side 3 cm = 2 (a triangle facing upwards + a triangle facing downwards)

Summing them up, we have 20 triangles in total.

Solution:

The Password.

Explanation:
Clues 2 and 5 are correct and rest are lies.

Solution:

No one understands