80 confidence interval

A random sample of 81 students was tested for the problem solving approach skills. The variance of the scores obtained from the sample was found to be 144. Find the 80% confidence interval for the variance and standard deviation. Assume that the variable is normally di..

A random sample of the assets (in millions of dollars) of 10 families of a colony is shown. Find the 80% confidence interval for the variance of the assets. Assume that the variable is normally distributed. 0.5 1 0.4 1.3 0.8 1.2 0.9 2 0.7 1.5 => between 0.158 and 0.529..

The prices of 1 gallon of premium gasoline in U.S dollars in a sample of seven foreign countries is shown. What is the point estimate for the mean? Find the 98% confidence interval of the mean for the prices of 1 gallon of premium gasoline in U.S. 3.80, 3.20, 3.80..

The formula for the confidence interval for a standard deviation is ________ . => III or II or IV or I..

When a 95% confidence interval is calculated instead of a 90% confidence interval with the same sample, the maximum error of estimate will be _____ . => either smaller or larger depending on sample size or the same or smaller or larger..

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..

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 ..

A random sample of 100 similar iron bars manufactured at a factory had a mean diameter of 6.43 mm and a variance of 0.032 mm 2 . Find 95% confidence interval and 99% confidence interval. Which interval is smaller? => (6.40, 6.47) and (6.38, 6.48) an..

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..