A distance of 425 km separates two trains moving towards each other at a speed of 200 km/hr each. What will be the distance between them after 1 hr 30 min, if they reduce their speed by half, every half an hour?
Note
Relative speed = (200 + 200) km/hr = 400 km/hr.
Distance covered in 1 hr 30 min
= {400 ☓ (1÷2) + 200 ☓ (1÷2) + 100 ☓ (1÷2)}km
= (200 + 100 + 50) km = 350 km.
Hence distance between the trains = (425 - 350) km = 75 km.