312-50V10 · Question #751
The change of a hard drive failure is once every three years. The cost to buy a new hard drive is $300. It will require 10 hours to restore the OS and software to the new hard disk. It will require a
The correct answer is D. $146. Using the risk formulas SLE x ARO = ALE, the total single loss is $440 (hardware + labor), and the annual loss expectancy divided across a 3-year failure cycle yields approximately $146 per year.
Question
The change of a hard drive failure is once every three years. The cost to buy a new hard drive is $300. It will require 10 hours to restore the OS and software to the new hard disk. It will require a further 4 hours to restore the database from the last backup to the new hard disk. The recovery person earns $10/hour. Calculate the SLE, ARO, and ALE. Assume the EF = 1(100%). What is the closest approximate cost of this replacement and recovery operation per year?
Options
- A$1320
- B$440
- C$100
- D$146
How the community answered
(32 responses)- A3% (1)
- B16% (5)
- C9% (3)
- D72% (23)
Why each option
Using the risk formulas SLE x ARO = ALE, the total single loss is $440 (hardware + labor), and the annual loss expectancy divided across a 3-year failure cycle yields approximately $146 per year.
$1320 would result from multiplying the total cost by 3 rather than dividing by 3, misapplying the ARO.
$440 is the SLE (Single Loss Expectancy) - the cost of one occurrence - not the annualized cost, so it ignores the ARO of 1/3.
$100 does not correspond to any correct application of the SLE, ARO, or ALE formulas given the values in the scenario.
SLE equals the hardware cost plus recovery labor: $300 + (14 hours x $10/hour) = $440. The ARO is 1/3 because failure occurs once every three years. ALE = SLE x ARO = $440 x (1/3) = $146.67, which rounds to approximately $146 - representing the expected annual financial impact of this risk.
Concept tested: Quantitative risk analysis: SLE, ARO, and ALE calculation
Source: https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-30.pdf
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