Without any halts, Sunil covers a distance at an average speed of 80 km/hr. With halts, he covers it at an average speed of 60 km/hr. How many minutes per hour does he stop?

1. Stoppage time per hour = (difference in speed / actual speed) × 60. 2. = (80 − 60)/80 × 60 = (20/80) × 60. 3. = 15 minutes per hour. _Source: RRB Group D CEN-02/2018 PYQ, Q.34._