Two cars X and Y start from two places A and B respectively which are 700 km apart at 9 a.m. Both the cars run at an average speed of 60 km/hr. Car X stops at 10 a.m. and again starts at 11 a.m. while the other-car Y continues to run without stopping. When do the two cars cross each other?

Both cars start at 9:00 AM 700 km apart and each travels at 60 km/h. In the first hour (9–10 AM) they close 60+60 = 120 km, leaving 580 km. Car X stops from 10–11 AM while Y continues, so Y alone closes another 60 km, leaving 520 km at 11:00 AM. From 11:00 AM both move toward each other again with combined speed 60+60 = 120 km/h. Time to meet = 520/120 = 13/3 hours = 4 hours 20 minutes after 11:00 AM, i.e., 3:20 PM. (Used standard rate-distance-time reasoning for opposite directions).