can someone verify my math please.

Discussion in 'Experienced Truckers' Advice' started by MNdriver, Apr 29, 2012.

  1. MNdriver

    MNdriver Road Train Member

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    So I have been getting a little more than anal about recording my mileages since I started with the Lucas Additive.

    Today I was going over my spread sheet and it's looking like the formulas are right.

    But got me questioning.

    My tank averages are not making sense compared to the weekly average. But I would trust my weekly averages over the tank.

    How can you have a weekly mileage average that is so much over the highest tank mileage average?
     
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  3. revelation1911

    revelation1911 Heavy Load Member

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  4. Pedigreed Bulldog

    Pedigreed Bulldog Road Train Member

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    First and foremost, how do you know that each time you filled the tank you filled it to the precise level? If you don't quite fill it up this tank, your MPG's will be higher...and then next time when you do, your MPG's will be lower.

    To a lesser extent, what certainty do you have that the fuel you pump is the same temperature each time you fill up? Fuel, like any liquid, expands as it warms and contracts as it cools. Warm fuel won't have as much energy/gallon as colder fuel...so while you may pump the same number of gallons, you'll see variation in what that fuel will do for you. If you happen to be using a pump that compensates for the temperature of the fuel (unlikely, but possible), then that gallon of fuel you pump could actually be more or less than a gallon...because you are pumping the volume of fuel at the current temperature that equals a gallon of fuel at 60 degrees.

    There are many other variables that go into fuel mileage...terrain...loads...etc...so any single tank isn't really a good indicator. Over several tanks, though, you start to see an average...because each independent variable begins to play a lesser and lesser role in the equation. Rather than calculating 1 tank full at a time, you are calculating the number of gallons purchased over several tanks vs. the miles run over several tanks.
     
  5. MNdriver

    MNdriver Road Train Member

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    where are you talking....

    tells me nothing with that.
     
  6. MNdriver

    MNdriver Road Train Member

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    exactly, that's why I trust the weekly mileage over the tank mileage.

    I have anti-siphon extensions into the tank and try to fill it to the same spot on the extension each time.


    The company tracks the mileage and they claim the truck has a history of 5.8 mpg. So if I have started to fuel outside the FlyinK/Pilot line and also using lucas, am I really getting that much better a fuel mileage?
     
  7. Pedigreed Bulldog

    Pedigreed Bulldog Road Train Member

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    88 + 93.3 + 140 + 50 = 371.3...not 283

    Mileage adds up to 2297

    2297 miles / 371.3 gallons = 6.18 mpg
     
    MNdriver Thanks this.
  8. Pedigreed Bulldog

    Pedigreed Bulldog Road Train Member

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    84.9 + 144.9 + 121.5 + 114 = 465.3....not 380

    Mileage is correct at 2769

    2769 / 465.3 = 5.95 mpg
     
  9. skateboardman

    skateboardman Road Train Member

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    your math is totally off, your gallons on the bottom line dont match what you put in.

    you are doing a tank by tank avg, then when you do the weekly total , you leave off a fillup, the math is fuzzy , you cant have avg of less than 8 by the tankful and then have a weekly avg of over 8. reanalyze how you did this
     
  10. MNdriver

    MNdriver Road Train Member

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    Thanks.

    I knew something wasn't looking right. I just couldn't pick it out.

    I have this in an excel spreadsheet and now I can't understand why the formula "=sum(e4:e7)" isn't giving that same number compared to "=e4+e5+e6+e7" Using that formula, I get the right number.
     
  11. MNdriver

    MNdriver Road Train Member

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    thanks,

    When I put in the "=e4+e5+e6+e7" type formulas and the numbers come out correct.

    the "=sum(e4:e7)" format is giving me errors in it. This formula is put in using the "autosum" button on the formula bar.

    THAT is bothersome.
     
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