Question

answer this question plz

Answer 1

Let the Total Distance to be Traveled be : 5D

Given that : The Car Covers 2/5th of the Total Distance with v₁ Speed

⇒ The Car Covers (2/5 × 5D) Distance with v₁ Speed

⇒ The Car Covers 2D Distance with v₁ Speed

We know that Time taken = (Distance traveled)/Speed

Time Taken by the Car to Travel 2D Distance = 2D/v₁

Given that : The Car Covers remaining 3/5th of the Total Distance with v₂ Speed

⇒ The Car Covers (3/5 × 5D) Distance with v₂ Speed

⇒ The Car Covers 3D Distance with v₂ Speed

We know that Time taken = (Distance traveled)/Speed

Time Taken by the Car to Travel 3D Distance = 3D/v₂

We know that Average Speed is the Ratio of Total Distance Traveled to that of Total time taken.

Total Distance Traveled = 5D

Total Time Taken to Travel 5D Distance = 2D/v₁ + 3D/v₂

⇒ $Average_s_p_e_e_d = \frac{5D}{\frac{2D}{v_1} + \frac{3D}{v_2}}$

⇒ $Average_s_p_e_e_d = \frac{5v_1v_2}{3v_1 + 2v_2}$

Option - (4) is the Answer