Question

The train travel from A to B and back to A. The ratio of the speed of onward journey to the speed of return journey is 5 ∶ 6. If the time taken in whole journey of 800 km is 16 hours. Find the speed of the train in return journey?
1. 44 Km/hr
2. 54 Km/hr
3. 55 Km/hr
4. 64 Km/hr
5. 75 Km/hr

Answer 1

Correct Answer - Option 3 : 55 Km/hr

Given:

The ratio of the speed of onward journey to the speed of return journey = 5 ∶ 6

Total distance in whole journey = 800 km

Total time taken in whole journey = 16 hours

Concept used:

Average speed = (2 × S₁ × S₂)/(S₁ + S₂)

Average speed = (Total distance)/(Total time)

Where,

S₁ → First speed

S₂ → Second speed

Calculations:

Let the speed of onward and return journey be 5x and 6x respectively.

So, the average speed of train in entire journey = (2 × 5x × 6x)/(5x + 6x) = 60x²/11

Average speed = 800/16

Now,

⇒ 60x² /11 = 50

⇒ x = 55/6

⇒ Speed of return journey is = 6 × 55/6 = 55 Km/hr