Actuarial Notes

Exam MAS-I Practice Question 31

Study guide: Exam MAS-I

Claim sizes X_1, \ldots, X_n are a random sample from a continuous distribution with CDF F, mean \mu and finite variance \sigma^2 > 0. Let \bar{X} be the sample mean, S^2 = \frac{1}{n-1}\sum (X_i - \bar{X})^2 the sample variance, and X_{(n)} the largest claim.

Determine which of the following statements are true.

  • I. Because E[S^2] = \sigma^2, the sample standard deviation S is an unbiased estimator of \sigma.

  • II. Whatever the shape of F, \text{Var}(\bar{X}) = \sigma^2/n.

  • III. For every x, P(X_{(n)} \le x) = F(x)^n.

  • A) I only

  • B) I and II only

  • C) I and III only

  • D) II and III only

  • E) The answer is not given by (A), (B), (C), or (D)

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