Question

A crow flies at a speed of 50 km/h for 3 hours and then at a speed of 40 km/h for further 2 hours. Find the average speed of the whole journey.

• A. 230 km/hr
• B. 46 km/hr
• C. 48 km/hr
• D. 36 km/hr

Answer 1

The correct option is B 46 km/hr

Speed = $\frac{Totaldistance}{Totaltime}$

Distance = Speed x time taken

First part of his journey, the crow flies at a speed of 50 km/hr for 3 hours:

Distance covered by crow = 50 x 3
= 150 km
Second part of his journey, the crow flies at a speed of 40 km/hr for 2 hours:
Distance covered by crow = 40 x 2
= 80 km
Hence, total distance covered in 5 hours = 150 km + 80 km = 230 km
Average speed of whole journey
= $\frac{Totaldistance}{Totaltime}$ = $\frac{230km}{5hours}$ = 46 km/hr