|Spoiler Inside: Solution to Puzzle||SelectShow>|
To work this out, start with 0 cases out of 1. This evaluates to less than 52.4% (even with rounding). Increase the number of cases and the number matching. This is 1 out of 2. Still less so increase both again to 2 out of 3. This is too high, so just increase the number of cases giving 2 out 4. Too low so increase both.
By continuing this process, you will come upon the solution which is 11 out of 21. 11 cases out of 21 is 52.38+% which rounds to 52.4%. The three-digit percentage does not seem too impressive now, does it?