Executives at A+ Mart grocery stores would like to expand to the rapidly growing town of Oakdale. Company analysts are trying to estimate future demand for grocery stores in Oakdale by looking at data from nearby cities.

Question

The analysts note the population of nearby cities (in thousands), x, and compare it to the number of grocery stores in each city, y.
The least squares regression line of this data set is:
y= 0.054x + 61.136

If a city has one thousand additional people, the least squares regression line predicts it will have_____ more grocery stores.

Answer 1

Substitute x+1 for x in the equation:

y = 0.054(x+1) + 61.136
y = 0.054x + 0.054 + 61.136
y = 0.054x + 61.19

This means that for each additional one thousand people in a city, the least squares regression line predicts it will have 0.054 more grocery stores.