CISA Practice Question: Information Systems Operations and Business Resilience
An IS auditor is reviewing the availability management process. The auditor calculates that the mean time between failures (MTBF) is 200 hours and the mean time to repair (MTTR) is 20 hours. What is the availability percentage?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
90.91%
Availability = MTBF / (MTBF + MTTR) = 200 / 220 ≈ 0.9091, or 90.91%.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
90.91%
Why this is correct
Correct calculation.
- ✗
99.00%
Why it's wrong here
Incorrect calculation.
- ✗
95.00%
Why it's wrong here
Incorrect calculation.
- ✗
80.00%
Why it's wrong here
Incorrect calculation.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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