You would like to construct a 95% confidence interval to estimate the population mean annual income for people over age 40 in your state. You choose a random sample of such incomes and compute the mean of the sample as 40,295.5 dollars with a standard deviation of 7563.4 dollars.(a) What is the best point estimate, based on the sample, to use for the population mean?dollars(b) For each of the following sampling scenarios, determine which distribution should be used to calculate the critical value for the 95% confidence interval for the population mean.(In the table, Z refers to a standard normal distribution, and t refers to a t distribution.)Sampling scenario Z t Could use either Z or t UnclearThe sample has size 15, and it is from a population with a distribution about which we know very little. Zt The sample has size 85, and it is from a non-normally distributed population with a known standard deviation of 7752. Zt The sample has size 20, and it is from a normally distributed population with an unknown standard deviation. Zt CheckSave For LaterSubmit Assignment

You would like to construct a 99% confidence interval to estimate the population mean price of milk (per gallon) in your city. You select a random sample of prices from different stores. The sample has a mean of 3.49 dollars and a standard deviation of 0.28 dollars.(a) What is the best point estimate, based on the sample, to use for the population mean?dollars(b) For each of the following sampling scenarios, determine which distribution should be used to calculate the critical value for the 99% confidence interval for the population mean.(In the table, Z refers to a standard normal distribution, and t refers to a t distribution.)Sampling scenario Z t Could use either Z or t UnclearThe sample has size 19, and it is from a normally distributed population with a known standard deviation of 0.31. Zt The sample has size 14, and it is from a normally distributed population with an unknown standard deviation. Zt The sample has size 80, and it is from a non-normally distributed population. Zt CheckSave For LaterSubmit Assignment

As part of an annual review of its accounts, a discount brokerage selected a random sample of 26 customers and reviewed the value of their accounts. The mean was $32,100, with a sample standard deviation of $8,550. (Use t Distribution Table & z Distribution Table.)What is a 95% confidence interval to estimate the mean account value of the population of customers? (Round your answers to the nearest dollar amount.)

Consider the following summary of a data set on the weekly earnings (in hundreds of dollars) of residents of NSW with a colleague degree: Number of observations : 25 Sample mean : 20.5 Sample standard deviation : 8 We assume that the weekly earning in the population is normally distributed with unknown mean and unknown variance. Please select the correct 95% confidence interval for the mean of the weekly earning (in hundreds of dollars) in the population. Group of answer choices [17.2, 23.8] [17.8, 23.2] [19.8, 21.2] [20.0, 21.0] [6.8, 34.2]

You want to compute a 90% confidence interval for the mean of a population with unknown standard deviation. The sample size is 30. The correct distribution value for calculating the required confidence interval is:-Group of answer choices1.961.64491.6991.6971.311

In a sample of 41 U.S. adults aged 18-24 who celebrate Halloween, the mean amount spent on a costume was $43.3 with a standard deviation of $14.9. Round answers to at least 4 decimal places.a) What parameter are we estimating? b) We can work this problem because: c) What is the point estimate of that parameter? d) What is the standard deviation of the sampling distribution for the sample means? e) Find the margin of error for a 90% confidence interval for the true average amount spent on a costume. f) We are 90% confident that the true average amount spent on a Halloween costume for U.S. adults aged 18-24 is between $ and $. Do not round between steps, and round answer to 4 decimal places.