A woman travels 282 km at 47 km/hr, a second distance of 120 km at 20 km/hr and a third distance of 496 km at 62 km/hr. Find her average speed for the whole journey (in km/hr).

Correct option is D

Given:

Distance₁ = 282 km, Speed₁ = 47 km/hr

Distance₂ = 120 km, Speed₂ = 20 km/hr

Distance₃ = 496 km, Speed₃ = 62 km/hr

Find average speed.

Formula Used:

Average Speed = $$\frac{D_1 + D_2 + D_3}{\frac{D_1}{S_1} + \frac{D_2}{S_2} + \frac{D_3}{S_3}}$$​​

Solution:

Total Distance = 282 + 120 + 496 = 898 km

Individual time 

​$$T_1 = \frac{282}{47} = 6 \text{ hr} \\ \ \\T_2 = \frac{120}{20} = 6 \text{ hr} \\ \ \\T_3 = \frac{496}{62} = 8 \text{ hr}$$​​

Total time = 6 + 6 + 8 = 20 hr

Average speed = $$\frac{898}{20}$$​ = 44.9 km/hr