Author's Thought

Author's Thought:
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Monday, November 5, 2012

Gas, Money, and Foes

Hey fellow reader,
Are you a nice guy or girl and enjoy lending a hand to fellow friends, or just strangers for the fun of it? Are you capable of saying NO? Well, if you can't, don't feel like it's your fault. You're simply a nice person! At least, that's what I tell myself after I give a ride to someone when I've already prioritized other things that I don't end up doing on time. Which brings me to my random but nevertheless math-related topic...

I swear to God, I hate not being given my money back, or the exact value back, at least. It's really annoying when someone owes me, let's say, $43.00 and only gives me two Queen E-Z's the Second. That can really put me off, since that person usually asks me for favors (rides, direct money, etc.) and the money he doesn't give me accumulates over time. Well, I just spent five of my precious minutes of college figuring out a formula for the exact gas-money people will owe me after a ride.

Let's see now. I've conducted a small research about my car and by the end I found out my car consumes an average (meaning highway and city together) of 9.4L/100KM. Easy to say that that means 0.094L/KM. I forget the last time I had an oil change but I estimate the cost of the oil and the oil filter to be about $50, and I change my car's oil every 5000 kilometers meaning that it costs me $0.01/KM for maintenance. Last but not least, the work I put into it (you don't have to take this number, I felt like it) is $0.016/KM. It's safe to say that we can combine both the maintenance and labor costs into a single one: $0.026/KM.

Now that we have all the information we need, I'll present to you my formula:

where km is the amount of kilometers you've traveled for the person, and y the cost of the gas you filled your car with.

Alright, now I'll give you a real-life example with which I constructed this formula:

So there you go. Feel free to use it; no copyright infringement or anything will be held against you. My life is too busy *cough cough*. Hopefully this'll help you and whoever you're helping and also keep you from gaining foes for overcharging! Haha... Yeah.

I know this isn't one of the best math posts I've ever published but at least it shows I'm still alive, and so is this blog!


  1. SO nice to read a post from you again! I have looked very carefully at this formula, and it works like a charm. I just looked at the units of each variable and number. (I wish codecogs worked in the comment field....sigh.) The 0.094y part is litre/km * $/litre, which algebraically cancels out the litres to leave $/km. Then in the brackets you have ($/km + $/km), which is also $/km. Then you multiply that by the 226 km, so you get $. Fantastic. But it's time to say no to whoever is taking advantage of your good nature! Tell whoever it is that you have a calculator, and you're not afraid to use it!

    1. Wow, I was not expecting an analytic comment from you, Miss! But then again, what can we not expect! Haha!

      Well, considering you did analyze, I'm happy that everything works and that you like it. Haha!

      And my friend moved out of college the past week-end, so I'll be fine. But I'll keep that calculator handy for any near-future commotions!