Problema Solution
an express train takes 1 1 2 hour less than a passenger train for covering a distance of 180 km. if the speed of the express train is 20 km/hr more than the passenger train, find the speed of both trains
Answer provided by our tutors
let
v1 = the speed of the express train, v1>=0
t1 = the speed of the express train
v2 = the speed of the passenger train, v2>=0
t2 = the speed of the passenger train
d = 180 km
since speed = distance/time we have:
v1 = d/t1 => t1 = d/v1
v2 = d/t2 => t2 = d/v2
the speed of the express train is 20 km/hr more than the passenger train:
v1 = 20 + v2
an express train takes 1 1/2 hour = 3/2 less than a passenger train for covering a distance of 180 km:
t1 = t2 - 3/2
plug t1 = d/v1 and t2 = d/v2 into the last equation:
d/v1 = d/v2 - 3/2
180/v1 = 180/v2 - 3/2
plug v1 = 20 + v2 into the last equation:
180/(20 + v2) = 180/v2 - 3/2
we find:
v2 = 40 km/hr
click here to see the step by step solution of the equation:
v1 = 20 + 40
v1 = 60 km/hr
the speed of the the express train is 60 km/hr.
the speed of the passenger train is 40 km/hr.