An engineer collected data from a random sample of water tank construction projects to build a statistical linear model that not only estimates the unit cost of water tank construction but also investigates the influence of certain factors on the unit cost of construction ($/ft3).
(i) For each independent variable, use the table below to indicate whether the model result is intuitive and to explain why or why not.
(ii) Use the model to estimate the total cost of an elevated steel tank of 50,000 ft3 capacity.