(a) Considering the income components in Problem 3.3 (same as the main components in Table 3.7), conjecture which sources of income are the most reliable.

(b) To check your conjecture, determine which income components show the greatest fluctuations? Compute the means, variances, standard deviations, and coefficients of variation for national income and each of its components expressed as a percentage of GDP for the post-World War II era and present the results in a table.

(c) Using the information from (b), compare your initial conjecture

(a) with the evidence in (b). (Be explicit about which measure of variability you use and why.)