What button on the HP 35s calculator is used to calculate the mean?

The correct choice for calculating the mean on the HP 35s calculator is the button labeled with S, which is the symbol for standard deviation (the upside-down Q). The mean, or average, of a data set can be calculated by entering the data into the calculator's statistical mode. When in this mode, pressing the appropriate statistical function allows the calculator to display the mean of the provided values.

Buttons like Σx are utilized for summing the values and are part of the process leading to calculating the mean but do not directly yield the mean itself. The S button, representing standard deviation, is associated with statistical operations that include the mean as part of its calculations. Understanding how these functions interact is crucial for accurate data analysis. In essence, the S button provides access to comprehensive statistical analysis, including mean calculation, making it the correct choice for this inquiry.