A and B go cycling in the same direction with speeds of 6 km/hr and 12 km/hr. A car from behind passes them in 9 and 10 seconds respectively. What is the speed of the car?
Q1. A and B go cycling in the same direction with speeds of 6 km/hr and 12 km/hr. A car from behind passes them in 9 and 10 seconds respectively. What is the speed of the car?
Answer: 66 km/hr
Explanation: Let car speed = v km/hr; equating car length: (v−6)×9/3600 km = (v−12)×10/3600 km; solving 9v−54 = 10v−120 gives v = 66 km/hr.