Algebra Story Problem

Question

You start 102 miles east of St. Louis and drive west at a constant speed of 59 miles per hour toward the town. (Assume that the road is straight and permits you to do this.) Find a formula for d, your distance east of St. Louis as a function of t, the number of hours of travel.

Answer 1

Jessica:

 

Let D be the distance east of St. Louis. Note that this distance is decreasing to 0, as you start 102 away East from SL.  In t hours of travel, you cover a distance of 59t miles going west. SO the distance left to be covered (the distance from St Louis eastward) is

 

D = 102 - 59t.

 

Incidentally, D becomes 0 (you reach SL) when t = 102/59 = 1.7288 hrs (1 hour and 44 minutes approx.)

 

Dattaprabhakar (Dr. G.)