Question 748063
 Kelsey drove an average of 50MPH for a 6-hour trip. During the first 4 hours, he drove 47MPH, what was the average speed, in MPH for last 2 hours?
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ave speed=distance/travel time
total distance for the entire 6-hr trip=6*50=300 mi
distance traveled during first 4 hours=4*47=188 mi
distance traveled during last 2 hrs=300-188=112 mi
ave speed for last 2 hours=112/2=56 mph (ans. B.)