Exam 6: Estimates and Sample Sizes With One Sample

For the next questions, find the critical value tα/2 that corresponds to the given confidence level. -90%; is unknown ; population appears to be normally distributed

For the next questions, determine which is the correct distribution. -95% Confidence Interval for . The sample data appear to come from a normally distributed population.

Find the minimum sample size required to estimate a population mean -Margin of error: 7 km; confidence level: 90%;

For the next questions, assume that a simple random sample has been taken and the population is normally distributed. Engineers assessing the variation in wait time at Starbucks, Dunkin Donuts, and Caribou Coffee determined that the standard deviation of the wait time for a sample of nine customers was 25.6 seconds. Use a 95% confidence level. -Find the critical value .

For the next questions, assume that a simple random sample has been taken, the population standard deviation is not known, and the population is normally distributed. Medical researchers studying cochlear implants, devices placed behind the bone in the ear to improve hearing, found the following number of implants over the last twelve years in children under 3 years old. Use a 90% confidence level and the following sample data: -Find the critical value .

Find the minimum sample size required to estimate a population proportion p . -Margin of error: four percentage points; confidence level: 95%; from a prior study, ˆp is estimated by the decimal equivalent 12.5%

For the next questions, determine which is the correct distribution. -95% Confidence Interval for . The sample data appear to come from a normally distributed population.

Find the minimum sample size required to estimate a population proportion p . -Find the margin of error E that corresponds to the above statistics and confidence level.

For the next questions, find the critical value tα/2 that corresponds to the given confidence level. -95%; is unknown ; population appears to be normally distributed

Find the minimum sample size required to estimate a population mean -Margin of error: 5 seconds; confidence level: 95%; seconds

Find the minimum sample size required to estimate a population mean -Find the margin of error E that corresponds to the above statistics and confidence level.

For the next questions, assume that a simple random sample has been taken, the population standard deviation is not known, and the population is normally distributed. Medical researchers studying cochlear implants, devices placed behind the bone in the ear to improve hearing, found the following number of implants over the last twelve years in children under 3 years old. Use a 90% confidence level and the following sample data: -Find the margin of error E that corresponds to the above statistics and confidence level.

Use the following confidence level interval limits to find the point estimate and the margin of error E . -Medical researchers, studying cochlear implants, devices placed behind the bone in the ear to improve hearing, find confidence interval of the mean number of implants over the past 12 years from 186.9 to 408 actually does contain the true value of .

Use the following confidence level interval limits to find the point estimate x and the margin of error E . -Biologists, studying the weights of mountain whitefish, in grams, find the confidence interval of the mean weights from 328.1 to 713.5 actually does contain the true value of .

Find the minimum sample size required to estimate a population proportion p . -Margin of error: three percentage points; confidence level: 90%; from a prior study, is estimated by the decimal equivalent 60.7%

Use the following confidence level interval limits to find the point estimate ˆp and the margin of error E . -An aquatic site adjacent to an old woodchipping mill is being studied to determine whether environmental liabilities exist from previous woodchipping operations. Because wood chips can leach toxic compounds into the water, environmental consultants measure the proportion of wood chips found in samples taken from various sediment cores. They find the confidence interval of the proportion of wood chips from .194 to .228 actually does contain the true value of p .

For the next questions, assume that a simple random sample has been taken, the population standard deviation is not known, and the population is normally distributed. Medical researchers studying cochlear implants, devices placed behind the bone in the ear to improve hearing, found the following number of implants over the last twelve years in children under 3 years old. Use a 90% confidence level and the following sample data: -Find the critical value .

For the next questions, find the critical value that corresponds to the given confidence level. -99%

For the next questions, find the critical value that corresponds to the given confidence level. -90%

Use the following confidence level interval limits to find the point estimate and the margin of error E . -Medical researchers, studying the improvement of individuals with Down Syndrome on a language and memory test after taking a certain drug, find the confidence interval of the mean test score improvement from 13.96 to 16.04 actually does contain the true value of .