Question

find the average speed of the car which travels the first 30 km at a speed of 40 km per hour and the remaining speed of 4 km per h and 4 minute per second at a speed of 60 km per h​

Answer 1

Answer:- 36 km/hr

Given train travels 12 minutes with speed 30 km \hr 

Then train travels = 30/60 × 12 = 6km

And train travels 8 minutes with speed 45 km\ hr

Then train travels = 45/60 × 8 = 6km

Then train travels distance in 12+8=20 minutes =6+6=12 km 

Then average speed = 12/20 × 60 = 36 km/hr.