Question

a man travels at a speed of 20 km/hr. and then returns at a speedof 30 km/hr. his average speed of whole journey is

• A. 25km/hr
• B. 24.5 km/hr
• C. 24 km/hr
• D. 25.5 km/hr

Answer 1

The correct option is C 24 km/hr

Given,

A man trads at a speed $V_1=20Km/h$ of distance $x$.

and Same distance $x$ with $v_2=30km/h$

Let the time travel from speed

$v_1=\frac{x}{20}$ (speed = dist/time)

where x is the constant distance.

Total distance travelled $=2x$.

Now,

Avg. speed = Total distance travelled/ Total time taken

$\Rightarrow \frac{2x}{\frac{x}{30}+\frac{x}{20}}=\frac{2x\times 60}{5x}$

$=24kmthr$

Option D = 24km/hr