Answer:
3:00 am
Explanation:
You want to know when a train leaving at 11:00 pm traveling east at 25 mph will catch up to one that left at 10:00 pm traveling east at 20 mph.
Head start
The train that left an hour earlier will have traveled 20 miles in that hour. The second train closes that gap at the rate of (25 mph -20 mph) = 5 mph. The time it takes to close the 20 mile gap at the rate of 5 miles per hour is ...
t = d/r
t = (20 mi)/(5 mi/h) = 4 h
Four hours after the second train leaves, the time will be 3:00 am.
The second train will catch up to the first one at 3:00 am.
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Additional comment
After 4 hours, the second train will have traveled 100 miles east. The first train will have traveled 5 hours at 20 mph, so also 100 miles east. Both trains are still in Colorado, so have not crossed the time zone boundary into Central Time. No time zone adjustment is needed for the time at which the trains meet.
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