Question

A university found that in an introductory statistics course, about 40% of the enrolled students will pass the course with A or B grades, 30% will pass with a C and 10% will obtained D or F grades. 20% of the students withdraw without completing the course. Assume that 20 students are registered for the course.

A. Compute the probability that 2 or fewer will withdrawB. Compute the probability that exactly 4 will withdrawC. Compute the probability that more than 3 will withdrawD. Compute the expected number of students who will withdraw from the class.

Answer 1

0.2061,0.2182,0.7939,4

Explanation:

Given that a university found that in an introductory statistics course, about 40% of the enrolled students will pass the course with A or B grades, 30% will pass with a C and 10% will obtained D or F grades. 20% of the students withdraw without completing the course

i.e if X is the no of students withdrawing then X has a constant probability of 0.20 (since independent)

X is binomial with n =20

a) the probability that 2 or fewer will withdraw

=
`P(X\leq 2)\\\\=0.2061`

B. Compute the probability that exactly 4 will withdraw

=
`P(X=4)\\=0.2182`

C. Compute the probability that more than 3 will withdraw

`P(X>3) = 0.7939`

D. Compute the expected number of students who will withdraw from the class.

=np = 20(0.2) = 4