Question

In 1999 there were 4076 J.C. Penney

stores and in 2003 there were 1078 stores. Write a linear

equation that gives the number of stores in terms of the

year. Let i = 9 represent 1999. Then predict the numbers

of stores for the years 2008 and 2010. Are your answers

reasonable? Explain.

Answer 1

- 749.5i + 10821.5

−2669.5

−4168.5

Explanation:

Given tgat:

Number of stores in 2003 (y2) = 1078

Number of stores in 1999 (y1) = 4076

1999 = i = 9

2003 = 13

y - y1 = m(x - x1)

m = slope = (y2 - y1) / (i2 - i1)

m = (1078 - 4076) / 13 - 9

m = - 2998 / 4

m = - 749.5

y - 4076 = - 749.5(i - i1)

y - 4076 = - 749.5(i - 9)

y - 4076 = - 749.5i + 6745.5

y = - 749.5i + 10821.5

Prediction for 2008 and 2010

2008 ; i = 18

y = - 749.5(18) + 10821.5

y = −2669.5

2010 ; i = 20

y = - 749.5(20) + 10821.5

y = − 4168.5