1. **Problem statement:** We analyze expected loss and insurance choices for Henry and Lucy given initial wealth $W_0=4975$ and a loss of 85% of wealth with probability 0.1.
2. **Expected loss (no insurance):**
$$\text{Loss} = 0.85 \times 4975 = 4238.75$$
Expected loss:
$$E[\text{loss}] = 0.1 \times 4238.75 = 423.875$$
3. **Henry's certainty-equivalent loss:**
Henry's utility is $u_H(x) = \sqrt{x}$.
Expected utility without insurance:
$$EU = 0.9 \times \sqrt{4975} + 0.1 \times \sqrt{736.25}$$
Calculate:
$$\sqrt{4975} \approx 70.534, \quad \sqrt{736.25} \approx 27.141$$
So:
$$EU \approx 0.9 \times 70.534 + 0.1 \times 27.141 = 66.191$$
Certainty-equivalent wealth $CE$ satisfies:
$$\sqrt{CE} = 66.191 \implies CE = (66.191)^2 \approx 4381.240$$
Sure loss equivalent:
$$4975 - 4381.240 = 593.760$$
4. **Lucy’s optimal insurance choice ($p=0.1$):**
Lucy’s utility is linear: $u_L(x) = x$.
Expected wealth gain per unit insurance:
$$0.1 \times 1 - 0.1 = 0$$
Lucy is indifferent across all insurance levels $\alpha$.
The largest such choice is $\infty$.
5. **Lucy’s optimal insurance choice ($p=0.2$):**
Expected gain per unit:
$$0.1 \times 1 - 0.2 = -0.1$$
Negative expected value means buy none:
$$0.000$$
6. **Henry’s optimal insurance choice ($p=0.2$):**
Final wealth:
No loss: $4975 - 0.2\alpha$
Loss: $736.25 + 0.8\alpha$
Expected utility:
$$EU = 0.9 \sqrt{4975 - 0.2\alpha} + 0.1 \sqrt{736.25 + 0.8\alpha}$$
First order condition (FOC) yields:
$$\alpha \approx 293.382$$
**Final answers:**
- Expected loss (no insurance): $423.875$
- Henry’s certainty-equivalent loss: $593.760$
- Lucy’s optimal insurance ($p=0.1$): $\infty$
- Lucy’s optimal insurance ($p=0.2$): $0.000$
- Henry’s optimal insurance ($p=0.2$): $293.382$
Expected Loss Insurance 41Ac7F
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