Here is a list of numbers: 15, 9, 12, 13, 6, 15, 18, 10, 11, 21. Find the mean, median and the mode.

To find the mean, we add all the numbers and divide by how many numbers there are. 15+9+12+13+6+15+18+10+11+21 = 130130/10 = 13The mean is 13.To find the median, we first arrange the numbers into order: 6, 9, 10, 11, 12, 13, 15, 15, 18, 21.Then we find the middle value by first adding 1 to the total amount of numbers then dividing by 2: (10+1)/2 = 5.5, we are lookinh for the 5.5th number.The number in the middle is between 12 and 13 so the median is 12.5The mode is 15 because it is the only number in the list that appears twice.