Speedometer must be calibrated every ___ months and you must pace someone for an _________________

• A. 3 months; short distance
• B. 12 months; long distance
• C. 9 months; generous distance
• D. 6 months; adequate distance

Answer: (D)

The question tests two related practices in speed enforcement: how often a speedometer should be calibrated and how to pace another vehicle reliably. Speedometer calibration should occur every six months to keep readings accurate and reduce the chance of reporting a speed that's off due to instrument drift. When you pace someone, you rely on your own speedometer to match the other vehicle’s speed, so you must do it over an adequate distance. That distance needs to be long enough to produce a reliable, consistent speed estimate given timing, reaction time, and road conditions. The combination of a six-month calibration interval and pacing for an adequate distance provides both instrument reliability and a defensible measurement method.