1. Assume that a sample is used to estimate a population proportion p. Find the 98% confidence interval for a sample of size 276 with 64 successes. Enter your answer as an open-interval (i.e., parentheses) using decimals (not percents) accurate to three decimal places. C.I. = ______

2. A political candidate has asked you to conduct a poll to determine what percentage of people support him. If the candidate only wants a 0.1% margin of error at a 97.5% confidence level, what size of sample is needed? When finding the z-value, round it to four decimal places.

= ______

3. You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately 67%. You would like to be 98% confident that your estimate is within 4.5% of the true population proportion. How large of a sample size is required? = _____

4. A surgeon would like to know how long it takes, on average, to complete a coronary artery bypass surgery. She samples 22 surgeries and logs the time it takes to complete each one, in hours: 4.9, 4.8, 5, 5.2, 4.4, 4.5, 5.1, 5, 4.8, 4.2, 4.7, 4.6, 5.1, 4.4, 4.6, 5, 5, 4.7, 5.1, 4.4, 4.3, 5 Assuming the population standard deviation is =0.28=0.28, construct a 99% confidence interval for the average time it takes to do a coronary artery bypass surgery. A. x=______ B. /2= _______ C. z2= ______ D. Margin of Error: E= _____ E. We are 99% confident that the mean amount of time it takes to complete a coronary bypass surgery is between _______ hours and _______ hours.

5. The mayor is interested in finding a 98% confidence interval for the mean number of pounds of trash per person per week that is generated in the city. The study included 140 residents whose mean number of pounds of trash generated per person per week was 35.7 pounds and the standard deviation was 7.4 pounds. Round answers to 3 decimal places where possible.

a. To compute the confidence interval use a ? z t distribution.

b. With98% confidence the population mean number of pounds per person per week is between ______ and _______ pounds.

c.If many groups of 140 randomly selected members are studied, then a different confidence interval would be produced from each group. About _____percent of these confidence intervals will contain the true population mean number of pounds of trash generated per person per week and about ______ percent will not contain the true population mean number of pounds of trash generated per person per week.

6. A psychologist is interested in constructing a 90% confidence interval for the proportion of people who accept the theory that a person's spirit is no more than the complicated network of neurons in the brain. 71 of the 787 randomly selected people who were surveyed agreed with this theory. Round answers to 4 decimal places where possible.

a. With 90% confidence the proportion of all people who accept the theory that a person's spirit is no more than the complicated network of neurons in the brain is between _______and _______.

b. If many groups of 787 randomly selected people are surveyed, then a different confidence interval would be produced from each group. About ______ percent of these confidence intervals will contain the true population proportion of all people who accept the theory that a person's spirit is no more than the complicated network of neurons in the brain and about _____ percent will not contain the true population proportion.