Math Problem Statement

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Part 1

A survey of adults in a certain country found that

8181​%

believed that protecting the rights of those with unpopular views is a very important component of a strong democracy. Assume the sample size was

Complete parts​ (a) through​ (f) below.

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Part 1

a. How many people in the sample felt this​ way?

The number of people in the sample that felt protecting the rights of those with unpopular views is a very important component of a strong democracy is

​(Round to the nearest integer as​ needed.)

Part 2

b. Is the sample size large enough to apply the Central Limit​ Theorem? Explain. Assume the other conditions are met. Select the correct choice below and fill in the answer​ box(es) to complete your choice.

​(Round to the nearest integer as​ needed.)

A.

​No, the sample size is not large​ enough, since the expected number of successes is

enter your response here

and the expected number of failures is

enter your response here​,

at least one of which is less than 10.

B.

​Yes, the sample size is large​ enough, since the expected number of successes is

729729

and the expected number of failures is

171171​,

both of which are greater than or equal to 10.

Your answer is correct.

C.

​No, the sample size is not large​ enough, since the estimated standard error is

enter your response here​,

which is less than 10.

D.

​Yes, the sample size is large​ enough, since the estimated standard error is

enter your response here​,

which is greater than or equal to 10.

Part 3

c. Find a​ 95% confidence interval for the proportion of adults in the country who believe that protecting the rights of those with unpopular views is a very important component of a strong democracy.

The​ 95% confidence interval is

​(. 519.519​,. 581.581​).

​(Round to three decimal places as​ needed.

Solution

Let's break down each part of the problem step-by-step:

Part 1: Number of people who felt this way

Given:

  • Percentage of adults who believe in protecting the rights of those with unpopular views: 81%81\%
  • Sample size: 900900

To find the number of people: Number of people=p^×n=0.81×900=729\text{Number of people} = \hat{p} \times n = 0.81 \times 900 = 729

Part 2: Central Limit Theorem Application

To apply the Central Limit Theorem, we need to check the conditions. The conditions require both the expected number of successes (npnp) and the expected number of failures (n(1p)n(1-p)) to be at least 10.

Given:

  • Sample size (nn): 900
  • Sample proportion (p^\hat{p}): 0.81

Expected number of successes: np=900×0.81=729np = 900 \times 0.81 = 729

Expected number of failures: n(1p)=900×(10.81)=900×0.19=171n(1 - p) = 900 \times (1 - 0.81) = 900 \times 0.19 = 171

Both 729 and 171 are greater than 10, so the sample size is large enough to apply the Central Limit Theorem.

Therefore, the correct choice is: B. Yes, the sample size is large enough, since the expected number of successes is 729 and the expected number of failures is 171, both of which are greater than or equal to 10.

Part 3: 95% Confidence Interval

Given:

  • Sample proportion (p^\hat{p}): 0.81
  • Sample size (nn): 900

First, calculate the standard error (SE): SE=p^(1p^)n=0.81×0.19900=0.1539900=0.0001710.0131SE = \sqrt{\frac{\hat{p}(1 - \hat{p})}{n}} = \sqrt{\frac{0.81 \times 0.19}{900}} = \sqrt{\frac{0.1539}{900}} = \sqrt{0.000171} \approx 0.0131

Next, calculate the margin of error (ME) using the critical value for a 95% confidence level (Zα/2Z_{\alpha/2} = 1.96): ME=Zα/2×SE=1.96×0.01310.0257ME = Z_{\alpha/2} \times SE = 1.96 \times 0.0131 \approx 0.0257

Finally, calculate the confidence interval: p^±ME=0.81±0.0257\hat{p} \pm ME = 0.81 \pm 0.0257 Lower limit=0.810.0257=0.7843\text{Lower limit} = 0.81 - 0.0257 = 0.7843 Upper limit=0.81+0.0257=0.8357\text{Upper limit} = 0.81 + 0.0257 = 0.8357

So, the 95% confidence interval is: (0.784,0.836)(0.784, 0.836)

Would you like further details or have any questions?

Here are five questions you might ask next:

  1. How do I interpret the confidence interval in context?
  2. What if the sample size was different? How would that change the confidence interval?
  3. How can I calculate a confidence interval for a different confidence level, like 99%?
  4. What is the relationship between the confidence interval and the margin of error?
  5. How can I determine if my sample proportion is significantly different from a hypothesized population proportion?

Tip: When interpreting a confidence interval, remember that it provides a range of values within which the true population parameter is likely to fall, given a certain level of confidence.

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Math Problem Analysis

Mathematical Concepts

Statistics
Sampling
Confidence Intervals

Formulas

Standard Error formula
Margin of Error formula

Theorems

Central Limit Theorem

Suitable Grade Level

High School