Question

The distance between two station A and B is 500 km . Two trains start from stations,at the same time on parallel tracks to cross each other . The speed of one train is 20 km/h less than that of the other .After three and quarter hours, the train are 45 km apart .find the speed of each train.​

Answer 1

Answer:

80 km/hr

100 km/hr

Step-by-step explanation:

Let speed of train A be x km/hr

therefore speed of train B = (x+20) km/hr

AB= 500 km/hr

distance between the trains = 45 km/hr

after 3 hrs 15 minutes= 13/4 hrs

two trains are moving opposite to each other hence,

Time interval = quarter hour (0.25 hour)

= 15 minute

both trains travel towards each other,

( their direction is opposite )

Relative speed = X + X + 20 = 2x + 20

Then apply formula,

speed = displacement / time interval

Time interval = displacement / speed

time = Distance between two trains / their speed

0.25 hour = 45/(2x + 20 )

45/(2x+20) = 0.25

45 = 0.5X + 5

0.5X = 45 - 5

0.5X = 40

X = 40/0.5

X = 80 km /h

speed of slower Train = X = 80 km / h

speed of faster Train = X + 20

= 80 + 20

= 100 km / h