Two places—P and Q are 400 miles apart. A car starts from P at a speed of 50 mph towards Q. After 75 minutes, another car starts from Q to P at a speed of 40 mph. At what time will the cars meet?

Correct option is A

Distance = 400 mile
Speed of 1st car = 50mph
Speed of 2nd car = 40 mph
Total distance covered by 1st car in 75 minutes = 50×75/60=62.5 mile
Remaining distance = 400 – 62.5 = 337.5
Relative speed = 50+40 = 90
Required time = 337.5/90=3.75
=3.75×60+75=300 min = 5 hrs.