Question

A car traveled the total distance of x in three equal intervals, first at a speed of 10 km/h. The second at a speed of 20 km/h and the last third at a speed of 60 km/h. Determine the average speed of the car over the entire distance x.

Answer 1

Given,

First -Third speed $=10km/h$

Second-Third speed $=20km/h$

So,

Let Total distance $=X$

So,

Total time $=\frac{X}{30}+\frac{X}{60}+\frac{X}{180}$

$=\frac{X}{18}$

So,

Average Speed $=$ Total distance is divided by the Total time

$=X\times \frac{18}{X}$

$=18km/h$