Answer: 1/12
Step-by-step explanation:
The notation
means "the overlapped region between circles A and B". There is only one value in this region, and it is the "8". This is in the lower half of this region as the upper half is empty.
There are 12 values in the set {2,4,6,8,10,12,14,16,18,20,24} which we can see by counting them out, or we can note how 24 = 2*12 and how we started with 2 = 2*1. So basically we have...
- 2 = 2*1
- 4 = 2*2
- 6 = 2*3
- 8 = 2*4
- 10 = 2*5
- 12 = 2*6
- 14 = 2*7
- 16 = 2*8
- 18 = 2*9
- 20 = 2*10
- 22 = 2*11
- 24 = 2*12
So again we have 1 value in the overlapped region between A and B, out of 12 values total. So that's why the answer is 1/12.