OG: Quant Reasoning Practice Question

GRE Quant Problem Solving
1

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In this question, can I choose radius of B as 0.1? So Radius of A= 12.1

In this case Difference of Circumfrence = 22.1 * 3.14 = 69

If radius of B = 1, Radius of A = 13
In this case Difference of Circumfrence = 24 * 3.14 = 75
So i Picked D. Though Answer is A.

I think I am doing something wrong in the first case. Need help to understand where i am going wrong here.

2

Try checking the difference of radii again in this case.