estimation and confidence intervals

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..

The number of miles per hour driven by a sales person on 14 different days is listed here. What is the point estimate for the mean? Find the 95% confidence interval of the mean for the average miles per hour. => 32.3 and 29.5 < μ < 35.1 or 31.5 and 31 < &mu..

A recent study of 50 people in a city found that 70% of the people have less than average incomes for the city. How many people should be surveyed to estimate the true proportion of people having an income of less than average with a 99% confidence interval 4% wide? =>..

An athlete wishes to estimate the mean number of miles run by him per day during practice session. The number of miles run by him on 7 days selected randomly is 7.2, 7, 7.5, 7.8, 7.6, 8 and 7.5. Based on the sample mean, what is the point estimate of the mean? Find the 95% ..

The rainfall readings (in millimeters) of 9 cities are listed here. Based on the sample, what is the point estimate of the mean? Find the 90% confidence interval of the population. 2.0, 2.8, 3.1, 4.4, 3.9, 2.6, 5.4, 4.7, 5.2 => 3.79 and 2.87 < μ < 4.71 or 3.9 ..

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..

The manager of a company wishes to estimate the average age of the present employees. From the past records, the standard deviation is found to be 8 years. A sample of 100 employees are selected and the mean is found to be 42.8 years. Find the 99% confidence interval o..

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

A teacher wishes to estimate the average weight of 10 students of grade 6 taken randomly. The weight(in pounds) of the students are shown. Find the 99% confidence interval for the variance for the weights of students. Assume that the variable is normally distributed. 9..

Select the incorrect statement(s). I. If a confidence interval does not include H 0 , then a hypothesis test will reject H 0 . II. If a confidence interval include H 0 , then a hypothesis test will reject H 0 III.For testing H 0 , t distribution is appropriat..