A school contains students in grades 1, 2, 3, 4, 5, and 6. Grades 3, 4, 5, and 6 all contain the same number of students. There are twice this number of students in grade 2 and three times this number in grade 1. If a student is selected at random from a list of all the students in the school, what is the probability that she will be in grade 3?

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.