SOLUTION: Imogene's car traveled 770 mi averaging a certain speed. If the car has gone 7 mph faster, the trip would have taken 1 hour less. Find the average speed.

Question 969347: Imogene's car traveled 770 mi averaging a certain speed. If the car has gone 7 mph faster, the trip would have taken 1 hour less. Find the average speed.
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = her normal speed in mi/hr
= her faster speed in mi/hr
Let = her time in hours
when traveling at mi/hr
= her time in hours when
traveling at mi/hr
----------------------------------
Equation for traveling at normal speed
(1)
Equation for traveling at faster speed
(2)
--------------------------
(2)
and
(1)
(2)
(2)
(2)
(2)
Multiply both sides by
(2)
(2)
(2)
(2) ( by looking at it )
( time must be positive )
and
(1)
(1)
(1)
the average speed is 70 mi/hr
-----------------------------
check:
(2)
(2)
(2)
(2)
OK

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