Applying The Law Of Total Probability

Question

At a university, 60% of computers run the Windows operating system, 30% run an Apple operating system, and 10% run Linux. A particular virus affects 3% of Windows computers, 2% of Apple computers, and 1% of Linux computers. All of the following statements are true EXCEPT:

Accepted Answer

The overall probability a computer is infected is calculated as $$0.6*0.03+0.3*0.02+0.1*0.01$$, which equals 0.027.

Answer

Multiplying the probabilities along each branch of the tree is valid because the events are independent.

Answer

The overall probability that a computer is not infected is given by $$1 - (0.6*0.03 + 0.3*0.02 + 0.1*0.01)$$.

Answer

Each branch’s contribution (the product of the OS proportion and its virus rate) adds to form the overall infection probability.

Applying The Law Of Total Probability

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