Question

A train travels some distance with the speed of 30km/hr and returns with the speed of 45km/hr.Calculate the average speed of the train

Answer 1

Answer:

let d/2 be the distance covered by train with a speed of 30kmph in t1 hours

→t1=d/60

it covers d/2 distance with a speed of 45km/h in t2 hours

→t2=d/90

average speed = total distance/total time

→=d/(t1+t2)

→=1/(1/60+1/90)

→=1/(3+2)/180

→=180/5=36kmph