# Math Help - Couple of questions

1. ## Couple of questions

Find the best-fitting straight line to the given set of data, using the method of leasts squares. Find the correlation coefficient.
(a)
Best fitting line:
Correlation coefficient:
(b)
Best fitting line:
Correlation coefficient:
(c)
Best fitting line:
Correlation coefficient:
(d)
Best fitting line:
Correlation coefficient:

Cost Curve: Dean (Statistical Cost Estimation, Bloomiington, Ind.: Indiana University Press, page 342) made a statistical estimation of the cost-output relationship for a shoe store. The data for the firm is given in the following table.

4.5, 7, 9, 10, 15, 20, 33, 50 3, 3.3, 3.4, 3.5, 4.5, 5.5, 7.5, 12

Here, is the output in thousands of pairs of shoes, and is the cost in thousands of dollars. (a) Determine the best fitting line using least squares.

(b) Determine the best-fitting quadratic using least squares.

2. Originally Posted by redraider717
Find the best-fitting straight line to the given set of data, using the method of leasts squares. Find the correlation coefficient.
(a)
Best fitting line:
Correlation coefficient:
(b)
Best fitting line:
Correlation coefficient:
(c)
Best fitting line:
Correlation coefficient:
(d)
Best fitting line:
Correlation coefficient:
Given the small number of points for each problem I presume you have to calculate them by hand. Look in your book for the formulas. Then you need to calculate
$\bar{x} \text{ and } \bar{y}$

$\sum x_i \text{ and } \sum y_i$

$\sum x_iy_i$

$\sum (x_i)^2 \text{ and } \sum (y_i)^2$

Then plug these into your formulas for the slope, intercept, and correlation coefficient. It will take a little while to do this for each problem.

-Dan

3. He said we could do it with a calculator by just punching the numbers in, which is why he didn't go into great detail for these problems. Any idea how to punch them into a ti-83?

4. Originally Posted by redraider717
He said we could do it with a calculator by just punching the numbers in, which is why he didn't go into great detail for these problems. Any idea how to punch them into a ti-83?
I couldn't tell you that, exactly. Where's your manual for the calculator? You should be able to find instructions there. If you don't have one, try looking for it here.

-Dan