SOLUTION: A marketing research consultant hired by Coca-Cola is interested in determining the proportion of customers who favor Coke over other soft drinks. A random sample of 400 consumers

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Question 763481: A marketing research consultant hired by Coca-Cola is interested in determining the proportion of customers who favor Coke over other soft drinks. A random sample of 400 consumers was selected from the market under investigation and showed that 53% favored Coca-Cola over other brands.
Compute a 95% confidence interval for the true proportion of people who favor Coke. Place your LOWER and Upper limit rounded to 3 decimal place
Answer by EdwinL51(1) About Me  (Show Source):
You can put this solution on YOUR website!
Using the formula for Confidence Interval for a Proportion P-hat +/- z_a/2*sqrt((p-hat*q-hat)/n)=> 0.53 +/- (1.96*sqrt((0.53*0.47)/400) => 0.53 +/- (0.0489) => (0.4811,0.5789)
Lower and upper limits to 3 decimal places is 0.481 and 0.589.
Hope that helps.
Ed