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Consider an individual with income Y.

A) Suppose she has a utility function U = 20Y. Is she likely to buy insurance? Why?
B) Suppose she has a utility function of U=log(Y). Is she likely to buy insurance? Why?
C) Suppose she has a utility function of U=0.5Y². Is she likely to buy insurance? Why?
D) Suppose her income is $2,000 when healthy and $1,000 when sick. Suppose further that her probability of being sick is 0.20 and that her utility function is U = 200Y⁰•⁵. Calculate her expected income and expected utility.

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Final answer:

Different utility functions impact the likelihood of buying insurance. Linear and quadratic utility functions make it more likely to buy insurance, while a logarithmic utility function makes it less likely. The expected income and utility can be calculated by multiplying incomes by probabilities and using the utility function.

Step-by-step explanation:

A) Utility Function U = 20Y

If the utility function is U = 20Y, where Y represents income, the individual is likely to buy insurance. This is because with a linear utility function, the individual values income proportionally. Therefore, the individual would want to protect their income by purchasing insurance.

B) Utility Function U = log(Y)

If the utility function is U = log(Y), where Y represents income, the individual is unlikely to buy insurance. This is because the logarithmic utility function implies that the individual values income less proportionally as income increases. Therefore, the individual may not see the benefit in paying for insurance.

C) Utility Function U = 0.5Y²

If the utility function is U = 0.5Y², where Y represents income, the individual is likely to buy insurance. This is because the quadratic utility function implies that the individual values income more than proportionally as income increases. Therefore, the individual would want to protect their income by purchasing insurance.

D) Expected Income and Utility

To calculate the expected income, we multiply the income in each state (healthy and sick) by the respective probabilities and sum the results. In this case, the expected income is (0.80 * $2,000) + (0.20 * $1,000) = $1,800.

To calculate the expected utility, we use the expected income in the utility function. The expected utility is 200 * (1,800^0.5) = 12,727.92.

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