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IAI Actuarial Core Principles · Economic Modelling · Ruin theory

An insurer has adjustment coefficient R = 0.02 per ₹ lakh. Using Lundberg's inequality, which initial surplus u (in ₹ lakh) guarantees that the ruin probability is at most 1%? Take ln 100 = 4.605.

Set e^{-0.02u} ≤ 0.01, so 0.02u ≥ ln 100 = 4.605 and u ≥ 230.25 lakh. Lundberg's bound then guarantees ruin probability of at most one percent.

  1. Au ≥ 46.05
  2. Bu ≥ 92.1
  3. Cu ≥ 230.25Correct
  4. Du ≥ 23.03
  5. u ≥ 100

Explanation

We need e^{-0.02u} ≤ 0.01, so 0.02u ≥ ln 100 = 4.605, giving u ≥ 4.605/0.02 = 230.25. Option 1 divides by 0.1 and option 4 by 0.2, both errors. Option 2 multiplies by 0.02 incorrectly.

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