GMAT Math Practice Test #1

Answer D: Median is the value of the number in the middle position of a list of numbers arranged in increasing (or decreasing) order. The series after arrangement is 3, 4, 6, 9, 21, 24, and 56. The 3rd term is in the middle and its value is 9.

Key takeaway: Mean, median and mode are measures of central tendency of data. It is easy to find median. However the series must be arranged in an ascending or descending order before finding the median.