Marriage According to a Pew Research survey, about 27% of American adults are pessimistic about the future of marriage and the family. This is based on a sample, but assume that this percentage is correct for all American adults.
a) Using a binomial model, what is the probability that, in a sample of 20 American adults, 25% or fewer of the people in the sample are pessimistic about the future of marriage and family?
b) Now use a Normal model to compute that probability. How does this compare to your answer from part a?
c) Using a Binomial model, what is the probability that, in a sample of 700 American adults, 25% or fewer of the people of the people in the sample are pessimistic about the future of marriage and family?
d) Now use a Normal model to compute that probability. How does this compare to your answer from part c?

Respuesta :

Answer:

Using a binomial model, the probability can be calculated using the binomial probability formula. For this scenario, where n (number of trials) is 20, p (probability of success on each trial) is 0.27, and x (number of successes) is 5, the probability is obtained as follows:

(

5

)

=

=

0

5

(

20

)

×

(

0.27

)

×

(

0.73

)

20

P(X≤5)=∑

k=0

5

(

k

20

)×(0.27)

k

×(0.73)

20−k

b) To use a Normal model, the conditions for applying the Normal approximation to the binomial distribution need to be satisfied. If np and n(1-p) are both greater than 5, then a Normal distribution can be used. Calculate the mean

and standard deviation

for the binomial distribution, and then use the Z-score formula to find the probability.

c) Apply the same approach as in part a using the binomial model, with n = 700, p = 0.27, and x = 175.

d) Utilize the Normal model as in part b, checking the conditions for approximation and calculating the probability using the Z-score formula.

Keep in mind that the Normal approximation is more accurate for larger sample sizes, and the answers from the binomial and Normal models should be reasonably close for sufficiently large sample sizes.