Question

You research the average cost of a tank of gasoline for a certain type of car for several recent years to look for trends. The table shows your data. What is the equation for a line of best fit? How much would you expect to pay for a tank of gas in the year 2019?

Note: The table below shows the average cost for one tank of gasoline, not one gallon.


y = 1.006x + 26.40; $47.52
y = 1.006x + 26.40; $58.92
y = 26.40x + 1.006; $47.52
y = 26.40x + 1.006; $58.92

Answer 1

Because the initial value is $26.40, the line must pass through this when x is 0. Thus, the answer is either the first or the second equation.
Next, we calculate the difference between the year 2019 and 1998 and substitute it into the value of x.
2019 - 1998 = 21.
Substituting this into the equation:
y = 1.006(21) + 26.40
y = $47.52

Thus, the first option is correct.