Bob has recently been hired by a shop downtown to help customers with various co
ID: 3330419 • Letter: B
Question
Bob has recently been hired by a shop downtown to help customers with various computer related problems. Lately, two different viruses have been bugging many customers - virus Dummy and virus Smarty. It is estimated that 65% of the customers with virus problems are bothered by virus Dummy and the remaining 35% by virus Smarty. If the computer is infected by virus Dummy, Bob has a 90% chance of fixing the problem. However, if the computer is infected by virus Smarty, this chance is only 70%. If a virus-infected computer is randomly selected from the shop, what is the probability that it can be fixed by Bob?
Explanation / Answer
P(virus dummy) = 0.65
P(Virus smarty) = 0.35
P(fixed by Bob | computer is virus infected) = P(fixed by Bob | virus dummy) * P(virus dummy) + P(fixed by Bob | virus smarty) * P(virus smarty)
= 0.9 * 0.65 + 0.7 * 0.35
= 0.83