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?
