SOLUTION: Kimberly took three hours to drive to her friend�s home on the weekend. Her average speed was 85 km/h for the first two hours. What was her average speed for the last hour of the t

Question 827967: Kimberly took three hours to drive to her friend�s home on the weekend. Her average speed was 85 km/h for the first two hours. What was her average speed for the last hour of the trip if her average speed was 75 km/h for the whole trip?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Average speed is always:
( total distance ) / ( total time )
Let = her average speed for the last hr
Her total time was hrs
------------------------
For 1st 2 hrs:
distance =
distance =
------------------
For next hr:
distance =
------------------
Average for the whole trip:

Her average speed for the last hr was 55 km/hr

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