If 0 is the center of the circle above

boomgoesthegmat wrote:

If O is the center of the circle above, what fraction of the circular region is shaded?

A) 1/12
B) 1/9
C) 1/6
D) 1/4
E) 1/3

OA: C

Notice that the question does NOT ask us to find the actual area of the shaded region. Instead, it asks us to find what fraction of the circular region is shaded.

We know that the angle of the TOP unshaded part is 150 degrees, so we can also conclude that the angle of the BOTTOM unshaded part is also 150 degrees.

So, a TOTAL of 300 degrees is unshaded.

Since there are 360 degrees in the entire circle, we can see that 60 degrees is shaded.

60/360 = 6/36 = 1/6
So, 1/6 of the circle is shaded.
Answer: C

Related Resources
The following video covers the concepts/strategies that are useful for answering this question:
- Pieces of Pi: https://www.gmatprepnow.com/module/gmat ... /video/878

Cheers,
Brent