R jogs at twice the speed of walking and runs at twice the speed of jogging. From his home to office, he covers half of the distance by walking and the rest by jogging. From his office to home, he covers half the distance jogging and the rest by running. What is his average speed (in km/h) in a complete round from his home to office and back home if the distance between his office and home is 10 km and he walks at the speed of 5 km/h?

Question

Question

This question was previously asked in

SSC CGL 2022 Tier-I Official Paper (Held On : 05 Dec 2022 Shift 1)

Answer 1

Given:

R jogs at twice the speed of walking and runs at twice the speed of jogging.

The distance between his office and home is 10 km

He walks at the speed of 5 km/h

Concept used:

Average speed = Total distance/Total time taken

Calculation:

R's jogging speed = 5 × 2

⇒ 10 km/h

R's running speed = 10 × 2

⇒ 20 km/h

Now,

At the time of going to his office time taken = 5/5 + 5/10

⇒ 1 + 0.5

⇒ 1.5 hours

At the time of returning to his home time taken = 5/10 + 5/20

⇒ 0.5 + 0.25

⇒ 0.75 hour

So, total time = 1.5 + 0.75

⇒ 2.25 hours or 9/4 hours

Total distance = 20 km [To and fro]

Average speed = 20/(9/4)

⇒ \(\frac{{80}}{9}\)

∴ His average speed (in km/h) in a complete round from his home to office and back home is \(\frac{{80}}{9}\).