Math Problem Statement

A CBS News poll conducted June 10 and 11, 2006, among a nationwide random sample of 651 adults, asked about their party affiliation (Democrat, Republican, or none) and their opinion of how the US economy was changing ('getting better,' 'getting worse,' or 'about the same'). Respondents were asked to answer several questions related to probabilities of these events based on the data table provided.

Solution

Let's break down the problem systematically and answer each question step by step based on the data provided.

Data Summary:

BetterSameWorseTotal
Republican3810444186
Democrat1287137236
None2190118229
Total71281299651

Part a: What percent of survey respondents identified themselves as Republicans?

This is a marginal probability: P(Republican)=Number of RepublicansTotal respondents=186651.P(\text{Republican}) = \frac{\text{Number of Republicans}}{\text{Total respondents}} = \frac{186}{651}.

Calculating: P(Republican)=18665128.6%.P(\text{Republican}) = \frac{186}{651} \approx 28.6\%.

Part b: What percent of survey respondents thought the economy was getting worse and were Republicans?

This is a joint probability: P(Republican and Worse)=Number of Republicans who thought the economy was getting worseTotal respondents=44651.P(\text{Republican and Worse}) = \frac{\text{Number of Republicans who thought the economy was getting worse}}{\text{Total respondents}} = \frac{44}{651}.

Calculating: P(Republican and Worse)=446516.8%.P(\text{Republican and Worse}) = \frac{44}{651} \approx 6.8\%.

Part c: What percent of Republicans thought the economy was getting worse?

This is a conditional probability: P(Worse | Republican)=Number of Republicans who thought the economy was getting worseTotal Republicans=44186.P(\text{Worse | Republican}) = \frac{\text{Number of Republicans who thought the economy was getting worse}}{\text{Total Republicans}} = \frac{44}{186}.

Calculating: P(Worse | Republican)=4418623.7%.P(\text{Worse | Republican}) = \frac{44}{186} \approx 23.7\%.


Final Answers:

  • a) 28.6%28.6\%
  • b) 6.8%6.8\%
  • c) 23.7%23.7\%

Let me know if you'd like a detailed explanation for any part or clarification!


Follow-up Questions:

  1. What is the percentage of Democrats who thought the economy was "about the same"?
  2. What is the probability that a respondent was unaffiliated and thought the economy was "getting better"?
  3. How many total respondents thought the economy was "getting worse" regardless of party affiliation?
  4. What percent of all respondents thought the economy was "about the same"?
  5. What is the conditional probability that a Democrat thought the economy was "getting worse"?

Tip: Always verify if probabilities sum to 100%100\% across all categories as a quick check for accuracy.

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Math Problem Analysis

Mathematical Concepts

Probability
Marginal Probability
Joint Probability
Conditional Probability

Formulas

P(Event) = (Number of favorable outcomes) / (Total outcomes)
Joint Probability: P(A and B) = (Number of cases satisfying A and B) / (Total cases)
Conditional Probability: P(A | B) = (Number of cases satisfying both A and B) / (Number of cases satisfying B)

Theorems

Definition of Probability
Conditional Probability Rule

Suitable Grade Level

Grades 10-12