Question

A person travels for 4 hours at speed of 30 km/hr and for 6 hours at the speed of 40km/hr. At the end of it, he finds that he has covered 75% of the total distance. At what average speed should he travel to cover the remaining distance in 3 hours?

Answer 1

Given that the person travel 4hrs with speed 30km/h
$speed = \frac{distance}{time } \\ \\ 30 = \frac{dis}{4} \\ \\ distance = 120km$
Now simillarly
For the next 6hrs

$40 = \frac{dis}{6} \\ \\ distance = 240km$
Now total distance covered = 120+240km
=360km
Given
360 is 75% of total distance

$360 = \frac{75}{100} \times total \: s \\ \\ total \: s = 480km$
So the distance left to cover=480-360=120km

Now,
$s = \frac{d}{t} \\ \\ s = \frac{120}{3} \\ \\ s = 40 \: \: \frac{km}{h}$
Hope it helps you mate_____❣️