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IAI Actuarial Core Principles · Risk Modelling and Survival Analysis · Compound distributions and their applications in risk modelling

A compound Poisson random variable S has Poisson parameter 4 and claim amounts X with E[X] = 3,000 and E[X^2] = 15,000,000 (in rupees). What is the variance of S?

For a compound Poisson distribution the variance equals lambda times the second moment of the claim size: 4 x 15,000,000 = Rs 60,000,000. Using the variance of X instead of E[X^2] would understate the result.

  1. ARs 36,000,000
  2. BRs 60,000,000Correct
  3. CRs 48,000,000
  4. DRs 12,000
  5. Rs 96,000,000

Explanation

For compound Poisson, Var(S) = lambda E[X^2] = 4 x 15,000,000 = 60,000,000. Using lambda Var(X) = 4 x 6,000,000 = 24,000,000 would be a mistake, since it ignores the mean-squared part.

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