Exam 8: Nutrition

According to the Entertainment Software Association, the average age of "gamers" (those that routinely play video games)is 30 years old. A random sample of 33 gamers people had an average age of 32.7 years old. Assume that the population standard deviation for the age of gamers is 4.6 years. Use a 90% confidence interval to test the validity of this report and choose the one statement that is correct.

The U.S. Census Bureau would like to estimate the average square footage of a new single-family home with a 95% confidence interval and a margin of error within plus or minus 200 square feet. Assuming the standard deviation for the square footage of new single-family homes is 850 square feet, the required sample size is ---------.

The average natural gas bill for a random sample of 26 homes in the 19808 zip code during the month of March was $305.30 with a sample standard deviation of $46.50. The critical value for a 95% confidence interval around this sample mean is __________ .

A _______ is a single value that best describes the population of interest.

A random sample of 13 hotels in Boston had an average nightly room rate of $172.10 with a sample standard deviation of $23.90. The approximate standard error of the mean for this sample is --------.

A 100% confidence interval is more accurate than a 90% confidence interval and is therefore more preferable.

The degrees of freedom are used to determine the critical z-score for the normal distribution when calculating a confidence interval.

The average natural gas bill for a random sample of 26 homes in the 19808 zip code during the month of March was $305.30 with a sample standard deviation of $46.50. The margin of error for a 98% confidence interval around this sample mean is -----.

When determining the sample size required for a 95% confidence interval for the population mean, the sample mean needs to be known.

A random sample of 17 hotels in Boston had an average nightly room rate of $165.40 with a sample standard deviation of $21.70. The 90% confidence interval around this sample mean is___ .

Dr. Jordan operates a dental practice with 315 patients and she would like to estimate the proportion of her patients that have dental insurance from their employers. A random sample of 110 patients found that 40 had insurance coverage. The 95% confidence interval to estimate the proportion of patients with dental insurance is _____________.

The definition of a 90% confidence interval is that we expect that close to 90% of a large number of sample means drawn from a population will produce confidence intervals that include that population's mean.

A statistics professor has 115 students in a statistics class and would like to estimate the number of hours each student studied for the last exam. A random sample of 41 students was found to study an average of 7.3 hours with a standard deviation of 1.9 hours. The 98% confidence interval to estimate the average number of hours studying for the exam is _____.

The National Center for Education would like to estimate the proportion of students who defaulted on their student loans for the state of Arizona. A pilot sample of 50 students with loans from Arizona found that eight had defaulted on their loans. The total sample size needed to construct a 95% confidence interval for the proportion of student loans in default with a margin of error equal to 4% is _____ .

A random sample of 30 business students required an average of 43.4 minutes to complete a statistics exam. Assume that the population standard deviation to complete the exam was 8.7 minutes. The margin of error for a 98% confidence interval around this sample mean is ------.

Steve's average golf score at his local course is 92.9 from a random sample of 60 rounds of golf. Assume that the population standard deviation for his golf score is 4.2. The standard error of the mean for this sample is ---------- .

A random sample of 60 business students required an average of 50.7 minutes to complete a statistics exam. Assume that the population standard deviation to complete the exam was 10.4 minutes. The 98% confidence interval around this sample mean is____ .

A random sample of 25 roundtrip flights between Philadelphia and Dallas has an average airfare of $393.50 with a sample standard deviation of $50.30. The critical value for an 80% confidence interval around this sample mean is ------.

The U.S. Census Bureau would like to estimate the average square footage of a new single-family home with a 95% confidence interval and a margin of error within plus or minus 100 square feet. Assuming the standard deviation for the square footage of new single-family homes is 850 square feet, the required sample size is ----------.

A random sample of 25 roundtrip flights between Philadelphia and Dallas has an average airfare of $393.50 with a sample standard deviation of $50.30. The 95% confidence interval around this sample mean is ------ .