# Question: Refer to the formula for a confidence interval in the

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.

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.

**View Solution:**## Answer to relevant Questions

Another question asked in the Gallup poll in Exercise 1 was: “Do you think that rich people in America today are happier than you, less happy, or about the same?” (Newport, 2012). Of the 1008 respondents, only 11% said ...Suppose 200 different researchers all randomly select samples of 400 individuals from a population. Each researcher uses his or her sample to compute a 95% confidence interval for the proportion that has blue eyes in the ...Explain whether the width of a confidence interval would increase, decrease, or remain the same as a result of each of the following changes: a. The sample size is doubled, from 400 to 800. b. The population size is ...Parts (a) through (d) below provide additional results for Case Study 21.1. For each of the parts, compute an approximate 95% confidence interval for the difference in mean symptom scores between the placebo and ...Confidence intervals are given for the relative risk of death for five specific causes of death, as follows: Circulatory (1.02 to 1.45), Cancer (0.83 to 1.37), Digestive (0.98 to 4.03), Respiratory (0.92, 3.02) and External ...Post your question