Can you elaborate more on question 18 (Backsolve)? I am having trouble understanding how you got 1683000 and 1717000.

I got those by multiplying 3,400,000 by 0.495 and 0.505 (49.5% and 50.5%). Since choice C said 49.5%, testing whether those two numbers are 34,000 apart is a good first step. Since they ARE, it’s also a good last step. 🙂