Student A uses a relative frequency distribution for a set of sample data and calculates the mean and standard deviation using formulas from Chapter 5. Student A justifies her choice of formulas by saying that since relative frequencies are empirical probabilities, her sample is represented by a probability distribution and therefore her choice of formulas was correct. Student B argues that since the distribution represented a sample, the mean and standard deviation involved are known as x and s and must be calculated using the corresponding frequency distribution and formulas from Chapter 2. Who is correct, A or B? Justify your choice.