Question

A university found that 10% of its students withdraw wthout completing the introductory statistics course. Assume that 20 students registered for the course. (Round your answers to four decimal places.) 

(a) Compute the probability that 2 or farmer will withdraw. 

(b) Compute the probability that exactly 4 will withdrawn 

(c) Compute the probability that more than a will withdraw 

(d) Compute the expected number of withdrawal

Answer 1

Solution:

Given:

n = 30

p = 0.10

x = Number of University students withdraw without completing the introductory statistics course follows a Binomial distribution with parameters n = 20 and p =0.10

Binomial probability formula :

Where q = 1 – p = 1 - 0.10 =0.90

Part a) Find:

P( 2 or fewer will withdraw) =........?

thus

Thus

Part b) Find:
P( X =4) =.............?

Part c) Find:

P( More than 3) = ..........?

P( X> 3) = .........?

thus find
P(X = 3) =........?

thus

Part d)

Expected number of withdrawals are: