Problema Solution
express commuter train #12 leaves the download station and travels at an average speed of 55 miles per hour towards the north side station, which is 66 miles away. twelve minutes later, express commuter train # 7 leaves the north side station and travels at an average speed of 45 miles per hour towards the downtown station.
at the moment when the two trains pass each other, how far (in miles) is the #12 train from the downtown station and how long ( in minutes) has the #12 train have been traveling?
Answer provided by our tutors
Initially 66 miles between trains.
Train #12 travels for 12 minutes before Train #7 leaves.
=> Travels for .2 hours before Train #7 leaves.
=> (55 mph)(.2 h) = 11 mi
Train #12 has travelled 11 miles before Train #7 leaves.
=> 55 miles between trains by the time that Train #7 leaves.
Train #12: 11 + 55t
Train #7: 45t
=> 55t - 11 = 45t
=> 10t = 11
=> t = 1.1 hours
Train #12 after 1.1 hours: (55)(1.1) = 60.5 miles
66 - (60.5) = 5.5 miles
Train #12 is 5.5 miles away from the station when the two trains pass and it has been travelling for 1.1 hours, or 66 minutes.