Question

On A 120km track , a train travels the first 30km at uniform speed of 30km/h How fast must the train travel the next the next 90km so as to average 60km/h for the entire trip ?

Answer 1

The answer is given below :

The train travels the first 30 km at uniform speed 30 km/h

and

let, the next 90 km is travelled at x km/h.

Then, the average speed is

= (30 + x)/2 km/h

Given that,

(30 + x)/2 = 60

=> 30 + x = 120

=> x = 120 - 30

=> x = 90

Therefore, the required speed for the last 90 km is to be 90 km/h.

Thank you for your question.

Answer 2

the train travels 1st 30km at the speed of 30km/
I.e,
d=30km
s=30km/h
let the train travels the next 90km=x km/h
30+x/2=60
then x=90
so ans is 90km/h