Car goes 360 km with average speed of 40 km/ hr then it goes 300 km with average speed of 30km/hr. Due to some problem in engine of car speed of car become 20 km/hr. the car take stop for 10 minutes on every 40 km and total time of stoppage is 1 hour. Car goes 20 km after last stoppage. Find the average speed of whole journey.

First segment: 360 km at 40 km/hr takes 9 hours. Second segment: 300 km at 30 km/hr takes 10 hours. For third segment at 20 km/hr with 10-min stops every 40 km: 6 stops × 10 min = 1 hour total stoppage, covering 240 km. After last stop, car goes 20 km more at 20 km/hr taking 1 hour. Total distance = 360 + 300 + 240 + 20 = 920 km. Total time = 9 + 10 + 12 + 1 + 1 = 33 hours. Average speed = 920/33 ≈ 27.88 km/hr. This is closest to 28.75 km/hr from option B.