Sriya with her family travelled from Bolpur to Suri by car at a speed of 40 km/hr and returned to Bolpur at a speed of 50 km/hr. The average speed for the whole journey is :
[A]44\frac{4}{9} km/hr
[B]44.78 km/hr
[C]45\frac{1}{2} km/hr
[D]45 km/hr

\mathbf{44\frac{4}{9}}\ km/hr
Average speed of journey =
= \left ( \frac{2xy}{x+y} \right )\ km/hr
= \frac{2\times 40\times 50}{40+50} = \frac{400}{9} = 44\tfrac{4}{9}\ km/hr
Hence option [A] is correct answer.