Final answer:
The probability that a murder victim in 2010 was killed by a stranger is found by subtracting the percentages of victims killed by family members and acquaintances from 100%, resulting in a probability of 22.2%.
Step-by-step explanation:
To calculate the probability that a randomly selected murder victim was killed by a stranger, you need to subtract the combined percentages of victims killed by family members and acquaintances from 100% since these are the only three categories given. According to the information provided, 24.8% were killed by a family member and 53% by an acquaintance. Thus, the percentage killed by strangers would be 100% - 24.8% - 53%.
First, add the percentages of family and acquaintance-related murders: 24.8% + 53% = 77.8%.
Then subtract this sum from 100% to find the percentage of stranger-related murders: 100% - 77.8% = 22.2%.
Therefore, the probability that a murder victim was killed by a stranger is 22.2%.