King Fahd University of Petroleum & Minerals

Mathematical Sciences

Stat319-Term033

Quiz #4 Sections: 3 & 4

Name: ID: Serial:

Question one: (5 points)

A class consists of 20 students, 8 of them practice morning sport. If a sample of 4 different students is selected at random.

a. What is the probability that at least three of them practice morning sport?

Solution:

b. What is the expected value of the number of the students who don’t practice the morning sport?

Solution:

In this case, consider

Question two: (5 points)

A school of 190 students take a certain exam. A sample of size 40 students is selected at random from this school. If the standard deviation of the marks of the 190 students in this school was 1.5 then

a. What is the sampling distribution for the sample mean

Solution:

b. What is the probability that will lie within two standard deviations form it’s mean?