medium · GMAT Quant
A cybersecurity firm uses an automated system to flag potentially malicious network requests. The prior probability that a request is malicious is 0.20. The system first checks for an unusual port number; the probability that a malicious request uses this port is 0.80, while the probability for a safe request is 0.10.
If a request is found to use an unusual port, and a second independent check for an invalid encryption signature is also positive (P(invalid|malicious) = 0.50 and P(invalid|safe) = 0.20), what is the probability that the request is malicious?
- dfrac56
- dfrac23
- dfrac12
- dfrac1625
- dfrac45
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