Short Answer
To calculate a 95% confidence interval for the proportion of Americans favoring American football, a sample of 1000 showed that 37% preferred the sport, resulting in a CI of (0.34, 0.40). Since the null hypothesis of 33% falls outside this range, it is rejected as a valid representation of the population’s preference.
Step 1: Understand the Sample and Proportion
To establish a 95% Confidence Interval (CI) for the proportion of people in the United States who favor American football, we work with a sample size of 1000 individuals. In this sample, 37% have identified American football as their favorite sport to watch on television, which converts to a probability of p = 0.37.
Step 2: Calculate the Confidence Interval
Using the formula for the confidence interval, apply the following parameters: the sample proportion (p), sample size (n), and the z-score for the desired confidence level. The formula is: CI = p ¬± z‚CA‚ao(p(1-p)/n). For 95% confidence, the z-score (z‚CA) is 1.96. Plugging in the values, we compute:
- CI = 0.37 ¬¨¬± 1.96 ‚Äöao(0.37 ‚à öo 0.63 / 1000)
- This results in a CI of (0.34, 0.40).
Step 3: Evaluate the Null Hypothesis
To determine if 33% (or 0.33) can be accepted as a reasonable representation of viewers who prefer American football, we compare it to our computed confidence interval limits: 0.34 and 0.40. Since 0.33 lies below the lower limit of the CI (0.34), we reject the hypothesis that the proportion of people who like football is 33%. Hence, it is unreasonable to believe that 33% accurately represents this population.