(a) A researcher recently surveyed 400 randomly chosen accidents that occurred on a Saturday evening. In the following table, each accident is classified by the number of vehicles involved and if alcohol contributed to the accident: Number of Vehicles Involved Alcohol a factor One Two Three or more Yes 50 100 20 No 25 175 30 (i) What percentage of accidents involved more than one vehicle? (ii) What proportion of accidents involved more than one vehicle with alcohol a contributing factor? (iii) Given that alcohol was a contributing factor, what proportion of accidents involved more than one vehicle? (b) An IT specialist estimates that the company's mainframe computer has a 15% chance of 'catching' a computer virus. However, she feels there is only a 7% chance of the computer 'catching' a virus that will completely disable its operating system. If the company's computer should catch a virus, what is the probability that the operating system will be completely disabled? Comment on the result