Question

When a person covers the distance between his park and office at 40 km per hr. he is late by 40 minutes. But when he travels at 50 km per hr. he reaches 20 minutes early. What is the distance between his office and his park?
1. 180 kms
2. 190 kms
3. 200 kms
4. 240 kms

Answer 1

Correct Answer - Option 3 : 200 kms

Given

A person speed 40 km per hr. reached office 40 minutes late

A person speed 50 km per hr. reached office 20 minutes early 

Let the distance between his office and park be x km.

Time is taken to reach office at 40 km per hr = x/40 hrs.

Time is taken to reach the park at 50 km per hr = x/50 hrs.

With the speed of 40 km per hr. he is 40 minutes late and at that of 50 km per hr. is 20 minutes early, so we can write. 

Calculation

= (x/40 − 40/60) = (x/50 + 20/60)

⇒ (x/40 − x/50) = (20/60 + 40/60)

⇒ (5x-4x)/200 = 60/60

⇒ x/200 = 1

∴ x = 200 kms