# 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 266450: 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 is 50 miles per hour.Answer by drk(1908)   (Show Source): You can put this solution on YOUR website!This is an RTD problem. We can create the following table based on given information. truck . . . . . .rate . . . . . .time . . . . . distance truck . . . . . . 42 . . . . . . . .4 . . . . . . . .168 truck . . . . . . 55 . . . . . . . .x . . . . . . . .55x totals. . . . . . 50. . . . . . . .4+x. . . . . . . 200 + 50x looking at column three we get 168 + 55x = 200 + 50x subtract 168 to get 55x = 32 + 50x subtract 50x to get 5x = 32 divide to get x = 6.4