Question

The price of gasoline at a service station increased from $1.65 per gallon last week to $1.82 per gallon this week. Sally paid $26.40 for gasoline last week at the station. How much more will Sally pay this week at the station for the same amount of gasoline?

Answer 1

Answer:

  $2.72

Step-by-step explanation:

The increase from last week is the fraction ...

  (new price)/(old price) -1 = (1.82/1.65) -1 = 17/165

so the amount of increase Sally will pay this week is ...

  17/165×$26.40 = $2.72

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Comment on the working

We could work this several ways. Perhaps most straightforward would be to determine how many gallons Sally bought last week, and multiply that by the change in price. Or, the number of gallons could be multiplied by the new price per gallon and the difference from the old purchase amount found.

If you look at the numbers, you see that we have effectively done it the first way. The change in price is $0.17 per gallon, and the number of gallons Sally bought is $26.40/$1.65.