Mrs. Baker’s students write word problems each week, and she selects one students word problem to display on the bulletin board each week. Each students name is placed in a bag from which she draws a name. What is the probability that an eighth grade student will NOT be selected?
EXPLAIN your process and give your answer as a % or simplified
There are a total of x students in the class where x is the sum of the students in all grades including the eighth grade. Let us assume the total number of students in the class is y where the total number of students in the eighth grade is z.
Therefore, the probability of selecting a student from the eighth grade is z/y.
The probability of not selecting a student from the eighth grade (i.e. selecting a student from all other grades combined) is 1 - z/y.
For example, if there are 50 students in the eighth grade out of a total of 250 students in the class, the probability of not selecting an eighth grade student would be 1 - 50/250 = 1 - 1/5 = 4/5.
Thus, the probability that an eighth grade student will NOT be selected is 4/5 or 80%.