In a nearby town, [tex]$56\%$[/tex] of adults read nonfiction books as a hobby, while only [tex]$39\%$[/tex] of teenagers read nonfiction books as a hobby. Let [tex]$\hat{p}_A$[/tex] and [tex]$\hat{p}_T$[/tex] be the sample proportions of adults and teenagers, respectively, who read nonfiction books as a hobby. Suppose 28 adults and 41 teenagers from this town are selected at random and asked if they read nonfiction books as a hobby.

Which of the following is the correct calculation and interpretation of the standard deviation of the sampling distribution of [tex]$\hat{p}_A - \hat{p}_T$[/tex]?

A. The difference (adult - teenager) in the sample proportions of those who read nonfiction books as a hobby typically varies about 0.003 from the true difference in proportions.

B. The difference (adult - teenager) in the sample proportions of those who read nonfiction books as a hobby typically varies about 0.015 from the true difference in proportions.

C. The difference (adult - teenager) in the sample proportions of those who read nonfiction books as a hobby typically varies about 0.055 from the true difference in proportions.

D. The difference (adult - teenager) in the sample proportions of those who read nonfiction books as a hobby typically varies about 0.121 from the true difference in proportions.



Answer :

To determine the correct answer, let's first recall that the standard deviation of the sampling distribution of the difference between two sample proportions, [tex]\(\hat{p}_A - \hat{p}_T\)[/tex], can be calculated using the following formula:

[tex]\[ \text{SD}(\hat{p}_A - \hat{p}_T) = \sqrt{ \frac{p_A (1 - p_A)}{n_A} + \frac{p_T (1 - p_T)}{n_T} } \][/tex]

Where:
- [tex]\( p_A \)[/tex] is the population proportion of adults who read nonfiction books, which is 0.56.
- [tex]\( p_T \)[/tex] is the population proportion of teenagers who read nonfiction books, which is 0.39.
- [tex]\( n_A \)[/tex] is the sample size of adults, which is 28.
- [tex]\( n_T \)[/tex] is the sample size of teenagers, which is 41.

Given these values, the standard deviation can be interpreted as follows:

"The difference (adult - teenager) in the sample proportions of those who read nonfiction books as a hobby typically varies about 0.121 from the true difference in proportions."

Thus, the correct answer is:

The difference (adult - teenager) in the sample proportions of those who read nonfiction books as a hobby typically varies about 0.121 from the true difference in proportions.