Which value on the number line is the best estimate of the center of the data set? A line plot with fourteen data values. Labels are at at twenty-five, thirty, and thirty-five. Tick marks are every one unit. Values appear as x marks above the line. Plot data values are one x mark above twenty-seven, two x marks above twenty-eight, three x marks above twenty-nine, three x marks above thirty, three x marks above thirty-one, zero x marks above thirty-two, one x mark above thirty-three, and one x mark above thirty-four.