A person goes to his office at one-fifth the speed at which he returns from his office. If his average speed during the whole journey is 20 km/hr, then what is the speed (in m/s) of the person while going to the office?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. .
Let the speed at which he returns from office be x.
Speed of going to office = x/5
Average speed = 2s1s2/(s1 + s2)
⇒ 2x(x/5)/(x + x/5) = 20
⇒ 2x2/5 = 120x/5
⇒ 2x = 120
⇒ x = 60
Speed while going to office = 60/5 = 12 km/h
Speed in m/sec = 12 × 5/18 = 10/3