Explanation:
first, for such questions, we sound always sorry the list of data points :
9, 10, 12, 15, 17
the mean is the sum of all data points divided by the number of data points. we have 5 data points.
mean = (9+10+12+15+17)/5 = 63/5 = 12.6
median is the data point for which half of the other data points are smaller, and the other half of other data points are larger.
so, for our 5 days points,
median = 12
the middle element in our sorted list.
mode simple defines the data value that appears the most frequently in the list.
in our case all values appear exactly once.
some people say then that the mode is all numbers in the list.
but most commonly we say that this list has no mode.