how to confidence interval

The formula for the confidence interval for a variance is _________ . => IV. or II. or III. or I...

What is meant by 95% confidence interval of the mean? => 95% of the specific sample means will fall within ± 1.96 standard errors of the population mean. or 95% of the specific sample means will fall within ± 2.58 standard errors of the population mean. or There is..

A restaurant owner wishes to find the 99% confidence interval of the mean number of visitors to the restaurant each day. How large the sample must be if he wants to be accurate within 10 persons? A previous study showed that the standard deviation of the visitors was 2..

To calculate the confidence interval for variance or standard deviation, a statistical distribution called ______ is needed. => chi-square distribution or binomial distribution or poisson distribution or multinomial distribution..

A researcher wishes to estimate the average daily wage (industrial composite) of industrial workers. A previous study showed that the standard deviation is $23. How large a sample must be selected if he wants to be 99% confident of getting an interval that contains the..

Select the correct statement(s). I. Increase in sample size will make the confidence interval of the population mean wider. II. A 90% confidence interval will be wider than a 99% confidence interval. III. Sample mean can never be the same ..

Select the correct statement(s). I. An interval estimate always contains the value of the parameter being estimated. II. To be more confident that the interval contains the true population mean, the interval shall be more narrow. => I only or II only or none ..

An automobile parts supplier wants to know how long car owners plan to keep their cars with them. A random sample of 20 car owners results in a standard deviation of 3.7 years. Find a 95% confidence interval for the variance and standard deviation. Assume that the vari..

The 95% confidence interval for the mean number of tablets in a bottle of calcium tablets is between 149.04 and 150.96. The standard deviation is 3 tablets. Find the size of the random sample that was used to determine this interval. => 40 or 38 or 6 or 150..

The 95% confidence interval for the mean weight of a sack of potatoes is between 4.92 and 5.08. If a random sample of 32 sacks was used to determine this interval, what was the standard deviation? => 0.04 or 0.16 or 3.92 or 0.23..