Concrete blocks production. A study published in the Global Scientific Journal (Vol. 8, 2020) examined the extent of the influence the selling price of bricks has on the sales volume in the city of Palangka Raya, Indonesia, by determining the relationship between the selling volume (y) and production cost (x). A total of n = 36 monthly data was collected based on annual financial reports from TB Nopia Santi, a business that is engaged in the production of concrete blocks. The analysis yielded a linear correlation of .5310 between the selling volume and production cost.

a. Give the equation of a linear model for the analysis.

b. Give a practical interpretation of the value r = . 5310.

c. Is the estimated slope of the line, part

a, positive or negative? Explain.

d. A test of the null hypothesis H0: r = 0 yielded a p-value of .001. Interpret this result.

e. Compute the coefficient of determination, r2 , for the regression analysis. Interpret the result.