Question

two trains left a station at the same time. one traveled north at a certain speed and the other traveled south at twice that speed. after 4 hours, the trains were 600 miles apart. how fast was each train traveling?

Answer 1

Speed of northbound train is 50 mph and speed of southbound train is 100 mph

Solution:

Let "s" be the speed of northbound train

Given that the other traveled south at twice that speed

Then, 2s is the speed of south bound train

After 4 hours, the trains were 600 miles apart

Since the train has left station at same time,

Distance = 600 miles

Time taken = 4 hours

Distance is given by formula:

$Distance = speed \times time$

Therefore,

$s \times 4 + 2s \times 4 = 600\\\\4s + 8s = 600\\\\12s = 600\\\\s = 50$

Thus speed of northbound train is 50 mph

Speed of southbound train = 2s = 2(50) = 100 mph

Thus speed of southbound train is 100 mph