Choice B is correct. The histograms shown have the same shape, but data set A contains values between and and data set B contains values between and . Thus, the mean of data set A is greater than the mean of data set B. Therefore, the smallest possible difference between the mean of data set A and the mean of data set B is the difference between the smallest possible mean of data set A and the greatest possible mean of data set B. In data set A, since there are integers in the interval greater than or equal to but less than , integers greater than or equal to but less than , integers greater than or equal to but less than , and integers greater than or equal to but less than , the smallest possible mean for data set A is . In data set B, since there are integers greater than or equal to but less than , integers greater than or equal to but less than , integers greater than or equal to but less than , and integers greater than or equal to but less than , the largest possible mean for data set B is . Therefore, the smallest possible difference between the mean of data set A and the mean of data set B is , which is equivalent to . This expression can be rewritten as , or , which is equal to . Therefore, the smallest possible difference between the mean of data set A and the mean of data set B is .
Choice A is incorrect. This is the smallest possible difference between the ranges, not the means, of the data sets.
Choice C is incorrect. This is the difference between the greatest possible mean, not the smallest possible mean, of data set A and the greatest possible mean of data set B.
Choice D is incorrect. This is the smallest possible difference between the sum of the values in data set A and the sum of the values in data set B, not the smallest possible difference between the means.