Two buses leave St. Louis from the same station. One leaves at 5:00 PM, traveling north to Chicago at an average speed of 50 mph. The second leaves at 5:30 PM, traveling south to New Orleans, also at an average speed of 50 mph. At what time are they 325 miles apart?

8:30 PM

Explanation:

v = Velocity

t = time

s = Distance

Let us find how much distance will the bus headed to Chicago will cover in half an hour

s = vt

s = 50*0.5

s = 25 miles

So, the gap between them is 25 miles when the other bus starts

So, each bus would cover the same distance which is 325-25/2 = 300/2 = 150 miles after taking into account the initial gap

s = vt

150 = 50t

150/50 = t

3 hours = t

Time taken for the gap to be 300 miles is 3 hours

Time taken for the gap to be 325 miles is 3+0.5 hours = 3.5 hours

So, the time when the gap will be 325 miles is

5:00 PM + 3:30

8:30 PM