A distance math problem?
Two trains leave at the same time going in opposite directions. One train is going 72 km/hr and the other is going 68 km/hr. After how long will the trains be 560 km apart?
Two trains leave at the same time going in opposite directions. One train is going 72 km/hr and the other is going 68 km/hr. After how long will the trains be 560 km apart?
Comments
68x+72x=560
solve for x
x=4
so 4hr
Speed of One Train, R1 = 72 km./hr.
Speed of Other Train, R2 = 68 km./hr.
Distance, D = 560 km.
Since the two trains are moving away from each other,
Overall Speed, Rt = R1 + R2
Rt= 72 + 68
Rt = 140 km./hr.
D = (Rt)t
560 = 140t
t = 560 / 140
t = 4
It will take 4 hrs. for the trains to be 560 km. apart.
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560 = distance of train 1 + distance of train 2
distance = rate * time
560 = 68t + 72t
560 = 140t
4 = t
Check. After 4 hrs train 1 goes 72*4=288 Km
Other train goes 68*4= 272 km
272 + 288 = 560
the trains are moving away from eacvh other at 72 + 68 = 140 km/h
d = rt
560 = 140t
t = 4h
You have to add the speed together to get the total distance covered in an hour
72+68=140mph separation
560/140=4
4 hours