Question

This probability distribution shows thedistribution for a Geometrytypical grade distributioncourse with 35 students.GradeABCD FFrequency510153 2Find the probability that a student earns agrade of D or F.p=[?

Answer 1

We are given a table of frequencies of each grade. To calculate the probabilities, we simply divide the reported number by the total number of students (35). So we have the table

Grade Pr(Grade)

A 5/35

B 10/35

C 15/35

D 3/35

F 2/35

As we want to calculate the probability that the student earns a grade D or a F, we simply add the probabilities of each grade. That is

`Pr(D\text{ or F\rparen=Pr\lparen D\rparen+Pr\lparen F\rparen = }(3)/(35)+(2)/(35)=(5)/(35)=(1)/(7)`

we also have that

`(1)/(7)=0.142857143`

which rounded to the nearest hundredth is 0.14. So the probability that a student earns a grade of D or F is 0.14