Question

A man travelled the first part of his journey at 160 km/h and the second part at 240 km/h, and covered a total distance of 3840 km to his direction in 20 hours. How long, in hours, did the second part of his journey last?
1. 8
2. 10
3. 12
4. 15

Answer 1

Correct Answer - Option 1 : 8

Given:

Speed of first part of journey = 160km/h

Speed of second part of journey = 240km/h

Total distance = 3840 km

Total time = 20hr.

Formula Used:

Distance = Speed × Time

Calculation:

Let time taken to travel in the first part = x hr.

Time taken to travel the second part = 20 - x hr.

Distance travelled in the first part = 160x

Distance travelled in the second part = 240(20 - x)

According to question:

Distance travelled in the first part = Distance travelled in the second part

⇒ 160x +  240(20 - x) = 3840

⇒ 160x + 4800 - 240x = 3840

⇒ - 80x = - 960

⇒ x = -960/-80

⇒ x = 12

Time taken in first half = x = 12hr.

Time taken in second half = 20 - x = 20 - 12 = 8hr.

∴ Time taken in second half = 8 hr.