To find the first quartile, we have to find the median of the lower data set.
Our real median is 17.5 approximately.
So taking the two points on the line before the 17.5 dot.
we have to add them together and divide by 2.
10 + 15 = 25
25/2 = 12.5
Therefore, our first quartile or q1 is 12.5
