Question

A motor cyclist completes a certain journey in 5 hours. He covers one-third distance at 60 km/hour and the rest at 80 km/hour. The length of the journey is :
1. 180 km
2. 240 km
3. 300 km
4. 360 km

Answer 1

Correct Answer - Option 4 : 360 km

Given:

Time taken by the motorcyclist = 5 hours 

Speed while covering 1/3rd of the distance = 60 km/h 

Speed while covering 2/3rd of the distance = 80 km/h

Formula used:

Time = Distance/Speed 

Calculation:

Let the length of the entire journey = 3a 

As per the question;

(3a × 1/3)/60 + (3a × 2/3)/80 = 5 

⇒ a/60 + 2a/80 = 5 

⇒ (4a + 6a)/240 = 5

⇒ 10a/240 = 5 

⇒ a = 120 

⇒ 3a = 3 × 120 = 360 

∴ The entire journey is of 360 km.