Mean is the average of all the numbers. To find the Mean of a set of numbers, add all the numbers together, and then divide that by the number of numbers.
Mean: (16 + 13 + 15 + 6 + 21 + 20 + 12 + 9 + 12) ÷ 9 = 13.8
Median is the middle number in the sequence, when lined up in numerical order from least to greatest.
Median: 6, 9, 12, 12, 13, 15, 16, 20, 21. The middle number is 13.
Mode is the value that occurs the most often.
Mode: 12 because 12 is the only value that occurs twice, which is the most.
Range is the difference between the smallest and largest value in the sequence.
Range: 21 - 6 = 15. The range is 15.
All together, the answers are 13.8, 13, 12, 15. The answer is the Second choice shown.
Hope that helps!
