1. 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 154 residents whose mean number of pounds of trash generated per person per week was 34.8 pounds and the standard deviation was 8.5 pounds.Round answers to 3 decimal places where possible.

27 13 11 9 12 19 14 14 9 21

a. To compute the confidence interval use a? t zdistribution.

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

c.If many groups of 154 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.

2. Assume that a sample is used to estimate a population mean. Find the 95% confidence interval for a sample of size 403 with a mean of 21.3 and a standard deviation of 13.5. Enter your answer as a tri-linear inequality accurate to 3 decimal places.

( )<< ( )

3. A botanist wishes to estimate the typical number of seeds for a certain fruit. She samples 45 specimens and counts the number of seeds in each. Use her sample results (mean = 69.6, standard deviation = 6.4) to find the 90% confidence interval for the number of seeds for the species. Enter your answer as anopen-interval(i.e., parentheses) accurate to 3 decimal places.

90% C.I. =( )

4. A researcher is interested in finding a 90% confidence interval for the mean number minutes students are concentrating on their professor during a one hour statistics lecture. The study included 107 students who averaged 32.8 minutes concentrating on their professor during the hour lecture. The standard deviation was 10.2 minutes.Round answers to 3 decimal places where possible.

a. To compute the confidence interval use a? t zdistribution.

b. With90% confidence the population mean minutes of concentration is between( )and( )minutes.

c.If many groups of 107 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 minutes of concentration and about( )percent will not contain the true population mean minutes of concentration.

5. A political candidate has asked you to conduct a poll to determine what percentage of people support her. If the candidate only wants a 4% margin of error at a 99% confidence level, what size of sample is needed? When finding the z-value, round it to four decimal places. ( )