Joel sailed for 3 hours at a speed of 20 miles per hour, then for 6 hours at 30 miles per hour and finally, 1 more hour at 40 miles per hour. What was the average speed of Joel during the whole sail?\n.\nOptions:\n(A) 25\n(B) 27.5\n(C) 28\n(D) 30\n(E) 32 Now, let's think a bit. Some random thoughts:
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3 hours at a speed of 20 miles per hour gives us Distance = 20*3 = 60 miles\n6 hours at a speed of 30 miles per hour gives us Distance = 30*6 = 180 miles\n1 more hour at 40 miles per hour gives us Distance = 40*1 = 40 miles\nTotal Distance = 60+180+40 = 280 miles\nTotal Time = 3+6+1 = 10 Hours\nAverage Speed = 280 / 10 = 28 Miles per hour
The final answer: (C).
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