What exactly are compartments in compartmental modeling? Can you broadly, yet intuitively, explain?

Cholesterol Cholesterol in human blood is necessary, but too much can lead to health problems. There are three main types of cholesterol: HDL (high-density lipoproteins), LDL (low-density lipoproteins), and VLDL (very low-density lipoproteins). HDL is considered “good” cholesterol; LDL and VLDL are considered “bad” cholesterol. A standard fasting cholesterol blood test measures total cholesterol, HDL cholesterol, and triglycerides. These numbers are used to estimate LDL and VLDL, which are difficult to measure directly. Your doctor recommends that your combined LDL/VLDL cholesterol level be less than 130 milligrams per deciliter, your HDL cholesterol level be at least 60 milligrams per deciliter, and your total cholesterol level be no more than 200 milligrams per deciliter. (a) Write a system of linear inequalities for the recommended cholesterol levels. Let x represent the HDL cholesterol level, and let y represent the combined LDL VLDL cholesterol level. (b) Graph the system of inequalities from part (a). Label any vertices of the solution region. (c) Is the following set of cholesterol levels within the recommendations? Explain. LDL/VLDL: 120 milligrams per deciliter HDL: 90 milligrams per deciliter Total: 210 milligrams per deciliter (d) Give an example of cholesterol levels in which the LDL/VLDL cholesterol level is too high but the HDL cholesterol level is acceptable. (e) Another recommendation is that the ratio of total cholesterol to HDL cholesterol be less than 4 (that is, less than 4 to 1). Identify a point in the solution region from part (b) that meets this recommendation, and explain why it meets the recommendation.

Franchise and Business Opportunities Annual Report contains information about franchise opportunities in the United States and Canada. A franchise fee is one of the expenses associated with owning a franchise. There are other expenses, such as startup, advertising, royalties, and so on. A large category of franchises is the fast-food business, which includes franchises such as baked goods, donuts, hamburgers, chicken, and hotdogs. Franchise fees (in thousands of dollars) for the fast-food category are as follow 21 25 25 18 44 20 25 15 19 24 28 30 25 25 25 25 10 25 35 20 20 15 10 20 25 30 13 30 15 28 15 35 24 40 15 20 35 5 50 30 25 40 15 25 15 55 33 23 30 10 FOR UNGROUPED DATA (USE 2 DECIMAL PLACES) MODE = || KURTOSIS = SKEWNESS = CV = FOR GROUPED DATA (USE 2 DECIMAL PLACES) MEAN = MEDIAN = MODE = CV =

D. In panel data, there are two key models, REM and FEM. Explain what the two models are, stating their key assumptions, differences, advantages and disadvantages.