Question
Based on the histogram below, does it appear that the population satisfies the requirement of a normal distribution? why or why not? Assume that 10% of the population believes that college is no longer a good investment. Find the probability that among 16 randomly selected people, exactly 4 believe that college is no longer a good investment. Find the probability that among 16 randomly selected people, at least 1 believes that college is no longer a good investment. The poll results were obtained by internet users logged on to the USA Today Website, and the internet users decided whether to ignore the posted survey or respond. What type of the sample is this? What does it suggest about the validity of the results?
Explanation / Answer
The distribution is Bin(n,0.1)
Here n =16
A) P(X=4) = 16C4 X 0.14 X (1-0.1)12 = 0.0514
B) P (Atleast 1) = 1- P(X=0)
=1- 16C0 X 0.10 X (1-0.1)16
= 1 - 0.1853 = 0.8147
C) The type of sample is a quota sample. The results will not be valid as the opinion of people who did not log on the USA Today Web site and people who ignored the survey is not considered.