Question: A small grocery store notices that the price it charges for oranges varies greatly throughout the year. In the off-season the price was as high as 60 cents per orange, and during the peak season they had special sales where the price was as low as 10 cents, 20 cents, and 30 cents per orange. Below are six weeks of data on the quantity of oranges sold (y) and price (x):
Assuming that the demand for oranges is given by the linear equation
y = α + βx + u
estimate the parameters of this equation. Calculate a 90% confidence interval for the quantity of oranges sold in week seven if the price is 25 cents per orange during that week.