Question

Irina walks $10km$ at $4km/h$ and then a further $8km$ at $5km/h$. Calculate Irina's average speed for the whole journey.

Answer 1

Since id is given Irina walks 10km at

4km/h .

So, velocity $=\frac{distance}{time}$

$\Rightarrow$ time $=\frac{distance}{velocity}$

$=\frac{10}{4}=2.5hrs....\left(1\right)$

Now, Irina walks 8 km at 5 km/h

$\Rightarrow$ time $=\frac{distance}{velocity}$

$=\frac{8}{5}=1.6hrs$....(2)

$\therefore$ Total time $=(2.5+1.6)hrs=4.1hrs$

Total distance is $(10+8)km=18km$

$\therefore$ Average speed $=\frac{18}{4.1}=\frac{Distance}{T.time}$

$=4.4km/hr$ Answer.