Question

The city of new orleans leaves union station in chicago at 6:00 am and travels south to new orleans. the train travels the 930.0 miles to new orleans at an average speed of 79.0 miles per hour. at the same time the city of chicago leaves new orleans and travels north to chicago. the train travels the 930.0 miles to chicago at an average speed of 81.1 miles per hour. how many miles south of chicago do the two trains pass each other? (miles are specified to the tenth of a mile so the answer must be specified to a tenth of a mile)

Answer 1

Answer: 460.6 miles South of Chicago

Explanation:

1) The City of New Orleans leaves Union Station in Chicago at 6:00 am and travels south to New Orleans. The train travels the 930.0 miles to New Orleans at an average speed of 79.0 miles per hour.

Scheme:


 →to south                                                    ←to north
                |----------------------|---------------------|
               A          x             X      930.0 - x    B
            6:00 am                                          6:00 am
           →                                                      ←
           v = 79.0 mi/h                                     v = 81.1 mi/h


=> x = 79.0 mi/h * t

2) at the same time the City of Chicago leaves New Orleans and travels north to Nhicago. The train travels the 930.0 miles to Chicago at an average speed of 81.1 miles per hour.

930.0 - x = 81.1 mi/h * t

3) How many miles south of chicago do the two trains pass each other?

Divide the two equations:

930.0 - x         81.1*t
------------- =   ----------
      x                 79*t

t cancels out =>

930.0 - x         81.1
------------- =   --------
     x                 79.0

Solve:

81.1x = 79.0(930.0 - x)

81.1x = 79.0 * 930.0 - 79.0x

81.1x + 79.0x = 73,470

=> 160.1x = 73,470

=> x = 73,470 / 160.1

=> x = 460.6 mi

4) Answer 460.6 miles South of Chicago.