Question

kim took 5 hours to complete a journey with an average speed of 80 km/h for the first 3 hours she travelled at an average speed of 60 km/h what was her average speed for the remaining time of the journey?

Answer 1

Given:

Kim took 5 hours to complete a journey with an average speed of 80 km/h. for the first 3 hours she travelled at an average speed of 60 km/hr.

To find:

Her average speed for the remaining time of the journey?

Calculation:

Let her average speed for the remaining time of the journey be v .

We know that average speed is defined as the total distance divided by the total time taken to cover that distance.

$\therefore \: avg. \: v = \dfrac{total \: distance}{total \: time}$

$\implies \: 80 = \dfrac{(60 \times 3) + (v \times 2)}{5}$

$\implies \: 80 = \dfrac{180 + 2v}{5}$

$\implies \: 180 + 2v = 80 \times 5$

$\implies \: 180 + 2v = 400$

$\implies \: 2v = 400 - 180$

$\implies \: 2v = 220$

$\implies \: v = 110 \: km {hr}^{ - 1}$

So, average speed for remaining time is 110 km/hr.

Hope It Helps.