A department store's annual sales (in millions of dollars) during the past 5 years were as follows. Annual Sales, y 5.8 6.2 7.2 8.4 9 Year, x 1 2 3 4 5

Question

A department store's annual sales (in millions of dollars) during the past 5 years were as follows.

Annual Sales, y	5.8	6.2	7.2	8.4	9
Year, x	1	2	3	4	5

(b) Derive an equation of the line L.

(c) Using the equation found in part (b), estimate the store's annual sales 8 years from now (x = 13). (Round your answer to one decimal place.)

Answer 1

Sa T

Well you need to find a line of best fit here using linear regression.

So if you have a TI-84 calculator, create two lists L1 - years, L2 - annual sales.

Click on STAT, EDIT and enter the data

Then STAT CALC, choose 4, go down to calculate and press enter

a = 0.86, b = 4.74

So y = 0.86 x + 4.74

r = 0.98 so there is nearly an exact linear relationship (r=1 for an exact one).

Then for (c) substitute x=13 here

Mike