# Algebra

posted by on .

The town of appleville recorded the following dates and populations.

YEAR POPULATION

1985 51.5
1985 53
1990 56
1995 62

Estimate the approximate population of Appleville in 1988 by finding an equation and then substituting.

HELP!!!

• Algebra - ,

Do this exactly the way w and I did the previous one

• Algebra - ,

• ok - ,

It says approximate so put it on the straight line between 1985 and 1990

what is that line?
m = (56-53)/(1990-1985) = 3/5
so y = (3/5)x + b
when x = 1985, y = 53 so
53 = (3/5) (1985) + b
53 = 1191+b
b = -1138
so
y = (3/5) x - 1138 between 1985 and 1990 approximately
y at 1988 = (3/5)(1988) - 1138
= 1192.8-1138 = 54.8 approximately

• Algebra - ,

Now before dinner is ready go back and understand the one w did and I explained.

• Algebra - ,

We can find this equation using different methods (Least square method, Lagrange interpolation polynomial method, ...)
Which you are applying?

• Algebra - ,

What is did here is called "linear interpolation" and I suspect it is what your text wants looking at the level of your previous problem. We could get more sophisticated fitting these four points with a cubic polynomial but based on the other problem I am quite sure your class is not there yet. I am quite sure by approximate they mean fit with a straight line between the closest points, linear interpolation.

• Algebra - ,

Yes Mgraph, but look at the previous question further down. I think this class is on straight lines. I could be wrong of course.

• Algebra - ,

I can not see them solving for a least square fit or using Lagrange polynomials.