SOLUTION: Lisa drove 60 miles, then increased her speed by 15 miles per hour for 135 miles. If the second part of the drive took 1 hour longer than the first part, find her average speed
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Question 1086507: Lisa drove 60 miles, then increased her speed by 15 miles per hour for 135 miles. If the second part of the drive took 1 hour longer than the first part, find her average speed
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Note that average speed is always:
[ total distance ] / [ total time ]
---------------------------------
Let = her time in hrs for the 1st part of the trip
(1)
(1)
------------------
For the 2nd part:
(2)
-------------------------------
Plug (1) into (2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
-----------------
Her total time was:
hrs
----------------------
Her total distance was:
and
Ave speed =
39 mi/hr
------------
check the math & get a 2nd opinion if needed
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