In: Statistics and Probability
In a survey, an Institute discovered that 40% of people who responded couldn’t remember any of the laws by the First Amendment. You decide to build a distribution for how many respondents could not recall any of the laws. You take on a random sample of 10 Americans.
A. What are the assumptions of a binomial distribution? Does the example match the assumptions?
B. What is the probability that the sample has exactly n successes, for n=1,2,3…10?
C. Plot the probabilities that were calculated in B.
D. Find the probability that the sample has at least 5 successes.
E. Find the probability that the sample has at most 3 successes.
A. Define X= number of respondents not being able to recall any of the laws out of 10 Americans.
p= proportion of people who responded but couldn’t remember any of the laws
Here the number of trials (i.e. the number of respondents chosen) is fixed, i.e. k=10
Each trial has two possibilities: either can recall or not
The trials are identical and independent in nature
The probability of success (i.e. not being able to recall) remains constant, i.e. p=0.4
Thus all the assumptions are satisfied and hence X~Binomial(10,.40)
B.
with p=.40.
C.
D. P(The sample has at least 5 successes)=
E. P(The sample has at most 3 successes.)
=P(X<=3)=P(X=0)+P(X=1)+P(X=2)+P(X=3)=0.006046618+..+.214991 =0.3822806