Which best represents the center of the data set below? average monthly grocery bill?

Measures of central tendency or measures of central location include median, mean and mode. They are used to locate the center of various distributions having a given data. Mean is the most common and used with both discreet and continuous data. Mean and mode have limitation when dealing with skewed data and hence median is preferred in such cases since it retains the central position even when the data is skewed. For this case Median is the appropriate measure of central tendency to represent the center of the data.

Basically, the median.