SOLUTION: 2.) A northbound train left the station at 6: 20 am, going at a rate of 55 miles per hour. If a southbound train left the same station at 7:20 am at a rate of 45 miles per hour, at

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: 2.) A northbound train left the station at 6: 20 am, going at a rate of 55 miles per hour. If a southbound train left the same station at 7:20 am at a rate of 45 miles per hour, at      Log On


   

Question 890098: 2.) A northbound train left the station at 6: 20 am, going at a rate of 55 miles per hour. If a southbound train left the same station at 7:20 am at a rate of 45 miles per hour, at what time was the distance between the two trains 275 miles?

Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
They are both moving away from the station. This analysis will use time quantities and not time points.

The northbound train travels for 1 hour before the southbound train begins its travel.

________________speed_________time_________distance
north___________55____________t+1___________55%28t%2B1%29
south___________45_____________t____________45%2At
TOTAL______________________________________275

The equation that can be written from that data table allows you to find how much time, t.
55%28t%2B1%29%2B45t=275
5t%2B55%2B45t=275
50t=275-55
50t=220
5t=22
highlight%28t=22%2F5=4%262%2F5%29 hours.
This is 4 hours 24 minutes.