SOLUTION: A truck travels for 4 hours at an average speed of 42 miles per hour. How much longer must the truck travel at an average speed of 55 miles per hour so that the average speed for t
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Question 904758: A truck travels for 4 hours at an average speed of 42 miles per hour. How much longer must the truck travel at an average speed of 55 miles per hour so that the average speed for the total trip will be 50 miles per hour? (Round your answer to one decimal place.) Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website! 4*42+x*55=50*(4+x)
168+x*55=200+50x
5x=32
x=32/5
x=6.4 hours 55 mph is added to 4 hours of 42 mph to get 10.4 hours at 50 mph
check
55*6.4+42*4=50(4+6.4)
352.0+168=50(10.4)
520.0=520.0
ok
