SOLUTION: A truck leaves St. Louis, Missouri, traveling north on I-55 at an average rate of 62 mph. At the same time, a bus leaves St. Louis traveling south on I-55 at an average rate of 55

Question 151564: A truck leaves St. Louis, Missouri, traveling north on I-55 at an average rate of 62 mph. At the same time, a bus leaves St. Louis traveling south on I-55 at an average rate of 55 mph. How long will it take until they are 936 miles apart?
Answer by Earlsdon(6294) (Show Source): You can put this solution on YOUR website!
You can use the distance formula for this problem:
and
where d = distance traveled, r = rate (speed) of travel, and t = time of travel.
For the first truck, r = 65 mph and we have to find t.
For the second truck, r = 55 mph and we have to find t but this will be the same value as for the first truck, and the sum of the distances traveled by the two trucks will be miles.

Substitute the d's from the above equations.

Divide both sides by 120.

It will take 7.8 hours (that's 7 hours and 48 minutes) for the trucks to be 936 miles apart.

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