An athlete running on a track falls short of the finish line by 10 m when she runs at a constant speed for a given time. If she increases her speed by 20%, she overshoots by 20 m in the same time. What is the length of the track?
You have the answer. Trap Analysis is why the other three were written.
Not a worked solution repeated four times — the specific reasoning error each wrong option was built to reward, and why this one tests execution slip.
See pricing50 are analysed free — try those first.