312-50V11 Question #486: Real Exam Question with Answer & Explanation

The correct answer is A: $62.5. ALE is calculated as SLE multiplied by ARO; applying the formula yields $62.50 using the given asset value, exposure factor, and failure frequency.

Information Security and Ethical Hacking Fundamentals

Question

The chance of a hard drive failure is known to be once every four years. The cost of a new hard drive is $500. EF (Exposure Factor) is about 0.5. Calculate for the Annualized Loss Expectancy (ALE).

Options

A$62.5
B$250
C$125
D$65.2

Explanation

ALE is calculated as SLE multiplied by ARO; applying the formula yields $62.50 using the given asset value, exposure factor, and failure frequency.

Common mistakes.

B. $250 is only the SLE and does not incorporate the ARO of 0.25, so it overstates the annualized loss by ignoring how frequently the event occurs per year.
C. $125 results from incorrectly using an ARO of 0.5 (dividing by 2 instead of 4), misrepresenting a once-every-four-years event as twice as frequent.
D. $65.2 does not correspond to any correct application of the ALE, SLE, or ARO formula using the values provided.

Concept tested. Quantitative risk analysis - ALE formula calculation

Reference. https://csrc.nist.gov/publications/detail/sp/800-30/rev-1/final

Topics

#ALE calculation#ARO#SLE#quantitative risk analysis

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