Freshmen in high school 2017-2018 when will i graduate

You will graduate in 2017 + 3 years (high school education years) = 2020
you will graduate in 2020.

You will graduate in the year 2021 if you do not take any extra classes, graduate early or fail to graduate. 

Period is the time it takes for one “cycle” to complete. in the parent sine function, period is 2*pi since sin(0) = 0, sin(pi/2) = 1, sin(pi) = 0, sin(3pi/2) = -1, and sin(2pi) = 0. at that point, the sequence repeats itself. i’m not sure if your graph is similar to the sine function since you didn’t provide a picture, but you can find the period by looking at a graph.