I have the following points and have asked to find the line of best fit equation.

Question

(2001, 17.60) and (2002, 18.75)

I keep coming up with y = 1.15x - 2283.55
but the answer book shows y = 1.15x + 12

1) What am I doing wrong with my equation?

This problem is about the average cost of baseball tickets over the years, so the +12 makes more sense in the context of the question, but I just cannot come up with that answer with my calculator.

2) I would assume that the 12 represents the amount that the tickets are going up, on average, per year?

3) They say that the y-intercept is (0, 12) -- how does this even make sense? If the x is the year and the y is the cost, in 0 years the cost was $12? Please help me understand this!!

Answer 1

I'm going to correct myself on #2 above and say the slope, 1.15, is representing that on average the cost of the tickets is going up 15% per year?

Answer 2

I also get your equation. The only thing I can see is that 2283.55/12 = 190
So maybe they are talking about the average ticket cost since baseball was invented 190 years ago.

If tickets cost $12 in 1811, then the costs shown in your plot are the prices after rising for 190 years.

Answer 3

the 15% angle is a good idea. Of course, now you have to do an exponential curve fit. To turn that into a straight line, use the log of the cost, turning your points into (2001, 1.246) and (2002,1.273)

Then your equation is
log y = mx+b