Question

If a car completes first half of journey at 40km/hr and second half in 60km/hr what is the average speed

Answer 1

let the total distance be 2x km

so, time taken in first half =x/40 hr
& time taken in next half =x/60 hr
so, total time=x/40 +x/60=(3+2)x/120=5x/120=x/24 hr

but as avg. speed=total distance/total time
so, avg. speed=2x/(x/24) =48 km/hr

Thanks..