Refer to the formula for a confidence interval in the Focus on Formulas section. a. Write the

Question:

Refer to the formula for a confidence interval in the Focus on Formulas section.
a. Write the formula for a 90% confidence interval for a proportion.
b. Refer to Example 20.6. Construct a 90% confidence interval for the proportion of smokers who would quit after 8 weeks using a nicotine patch.
c. Compare the 90% confidence interval you found in part (b) to the 95% confidence interval used in the example. Explain which one you would present if your company were advertising the effectiveness of nicotine patches.