I am not sure how to show you how to do a dot plot on this website, but to see how to do a dot plot
b) Put everything in order and find the middle
10, 10, 10, 20, 30, 30, 30, 30, 40, 50, 50, 50, 60, 60, 70, 70, 2040
^^
So 40 is in the middle, making it the median
c) Add all of the values together and divide by the total number of values.
10 + 10 + 10 + 20 + 30 + 30 + 30 + 30 + 40 + 50 + 50 + 50 + 60 + 60 + 70 + 70 + 2040 = 2660
2660 / 17 = 156.5