SOLUTION: A man travels up a hill at 12 mph. He realizes he forgot his lunch and goes down the hill the exact same way at 25 mph. The entire trip took 4.6 hours. What was his average speed t

Question 1069826: A man travels up a hill at 12 mph. He realizes he forgot his lunch and goes down the hill the exact same way at 25 mph. The entire trip took 4.6 hours. What was his average speed throughout the entire trip?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
speed*distance=time
took him 4.6 hours; let time going up the hill=x and time down the hill =4.6-x
12*x=distance up
(4.6-x)25=115-25x distance down, and they are equal
Therefore, 12x=115-25x
37x=115
x=3.108 hours
at 12 mph that is 37.3 miles
at 25 mph and 1.492 hours, that is 37.3 miles to check
The total trip was 74.6 miles in 4.6 hours. The average speed was 16.22 mph, closer to 12 mph uphill speed, since more time was spent going uphill.

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