Changes

But the average price of the gas ''I bought'' depends on how much gas I buy each week. For me, the average price of gas is the price of gas each week ''weighted by'' the amount of gas I actually bought each week.  

But the average price of the gas ''I bought'' depends on how much gas I buy each week. For me, the average price of gas is the price of gas each week ''weighted by'' the amount of gas I actually bought each week.  

For example, suppose that I did almost no driving on the first, second, and fourth weeks, and bought only one gallon because (for some reason) I wanted to keep the tank topped up, but that on the third week I was on vacation, took a trip, and used ten gallons. Since I did almost of my driving on the third week, the price of the gas '''I''' bought is going to be dominated by that third week. It is going to be close to $2.40 per gallon. If I hadn't bought any gas at all on the first, second, and fourth weeks, the price of gas on those weeks wouldn't have mattered at all. As it is, they don't vary very much.

For example, suppose that I did almost no driving on the first, second, and fourth weeks, and bought only one gallon because (for some reason) I wanted to keep the tank topped up, but that on the third week I was on vacation, took a trip, and used ten gallons. Since I did almost of my driving on the third week, the price of the gas '''I''' bought is going to be dominated by that third week. It is going to be close to $2.40 per gallon. If I hadn't bought any gas at all on the first, second, and fourth weeks, the price of gas on those weeks wouldn't have mattered at all. As it is, they don't matter very much.

If I look at the four receipts at the end of the month, I see:

If I look at the four receipts at the end of the month, I see: