4) A sample of 100 new cars sold in the USA shows that the mean price was $25,500. The standard deviation was $4,200. a) Find a 95% confidence for the mean price b) If we got the same information with a sample of 64 what effect if any would that have had on the length of the confidence interval c) The Automobile Retailers Association claims that the mean price is $23,000. Do we reject their claim? Explain your answer briefly.

A survey of 32,782 adults in 2004 indicated that 24.6% of adults were current smokers. A similar study conducted in 1995 of 40,000 adults indicated that 29.7% were current smokers. a. Find and interpret a point estimate of the difference between the proportion of current smokers in 1995, and the proportion of current smokers in 2004. b. A 95% confidence interval for the true difference is (-0.058,-0.045). Interpret. c. What assumptions must you make for the confidence interval i part b to be valid? (…) a. Find a point estimate of the difference between the proportion of current smokers in 1995 and the proportion of current smokers in 2004. (Round to three decimal places as needed.)

Please help with 6 a-b

A random sample of 64 shoppers showed that they spend an average of $27.31 per visit at the Sunday Mornings Bookstore. The standard deviation of the population is $2.14. Find the 90% confidence interval of the true mean. Please include all work showing how you found your answer.

The mayor is interested in finding a 95% confidence interval for the mean number of pounds of trash per person per week that is generated in the city. The study included 249 residents whose mean number of pounds of trash generated per person per week was 34.8 pounds and the standard deviation was 7.2 pounds. Round answers to 3 decimal places where possible. b. With 95% confidence the population mean number of pounds per person per week is between   ?  and   ?  pounds. c. If many groups of 249 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.

first picture is the background information

At a large high school, an assistant principal wants to know how intelligent the students at the school are. An intelligence test is administered to an SRS of 50 students, out of over 2000 students. The mean score was 115 and the standard deviation was 15. Construct a 99% confidence interval for the mean score of all students in the school. A) (109.32, 120.69) B) (119.58, 123.50) C) (110.87, 129.41) D) Can not be determined from the information given.

The mayor is interested in finding a 99% confidence interval for the mean number of pounds of trash per person per week that is generated in the city. The study included 236 residents whose mean number of pounds of trash generated per person per week was 33.6 pounds and the standard deviation was 8.7 pounds. Round answers to 3 decimal places where possible. b. With 99% confidence the population mean number of pounds per person per week is between    ?  and  ?  pounds. c. If many groups of 236 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.

Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 78 cookies and finds that the number of chocolate chips per cookie in the sample has a mean of 19.3 and a standard deviation of 2.1.   Find a 80% confidence interval for the number of chocolate chips per cookie for Big Chip cookies?   Round your answers to one decimal place.