Question

A Bus cover an equal distance at the speed of 200 km/hr, 400 km/hr and 600 km/hr, then find the average speed (approx.)of the bus for the whole journey. 
1. 327 km/hr
2. 320 km/hr
3. 430 km/hr
4. 420 km/hr

Answer 1

Correct Answer - Option 1 : 327 km/hr

GIVEN:

Different speed for the equal distance is 200 km/hr, 400 km/hr and 600 km/hr

FORMULA USED:

Average Speed = Total Distance/Total Time

CALCULATION:

Let the equal distance be d km

⇒ Average Speed = Total Distance/Total Time

\(⇒ \frac{{3d}}{{\frac{d}{{200}} + \frac{d}{{400}} + \frac{d}{{600}}}}\)

\( ⇒ \frac{{3d}}{{\frac{{6d \; + \; 3d \; + \; 2d}}{{1200}}}}\)

\(⇒ \frac{{3d \; \times\; 1200}}{{11d}}\)

⇒ 3600/11 

⇒ 327.27 km/hr ≈ 327 km/hr

∴ The average speed is 327 km/hr