Question

A water tanker can finish a certain journey in 10 hours at the speed of 38 km/hr. By how much should its speed be increased so that it may take only 8 hours to cover the same distance?​

Answer 1

Its speed should increase by 9.5km/hr

Explanation:

speed is calculated by distance divided by time

we know that it took the tanker 10 hours to drive 380km (38km times 10 hours)

so if we divide the 380km by 8 hours we see that he should be driving at 47.5km/hr in order to travel the same distance in 8 hours

the question asks by how much speed should it INCREASE, so we subtract the 38km from the 47.5km to find the difference in speed, which is 9.5km