You want to obtain a sample to estimate a population mean

Confidence Intervals

Question 1

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately sigma = 28.6. You would like to be 98% confident that your estimate is within 3 of the true population mean. How large of a sample size is required? Do not round mid-calculation.

Question 2

You want to obtain a sample to estimate how much parents spend on their kids birthday parties. Based on previous study, you believe the population standard deviation is approximately sigma = 54.6 dollars. You would like to be 99% confident that your estimate is within 4 dollar(s) of average spending on the birthday parties. How many parents do you have to sample?

Question 3

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately sigma = 29.8. You would like to be 95% confident that your estimate is within 2 of the true population mean. How large of a sample size is required?

Question 4

You measure 26 turtles' weights, and find they have a mean weight of 34 ounces. Assume the population standard deviation is 6.9 ounces. Based on this, what is the maximal margin of error associated with a 99% confidence interval for the true population mean turtle weight.

Give your answer as a decimal, to two places

Question 5

An engineer wishes to determine the width of a particular electronic component. If she knows that the standard deviation is 2.2 mm, how many of these components should she consider to be 99% sure of knowing the mean will be within ± 0.5mm?

22

129

105

622

12

Question 6

An engineer wishes to determine the width of a particular electronic component. If she knows that the standard deviation is 1.1 mm, how many of these components should she consider to be 80% sure of knowing the mean will be within ± 0.4mm?

16

13

4

6

11

Question 7

A political candidate has asked you to conduct a poll to determine what percentage of people support him. If the candidate only wants a 8% margin of error at a 99% confidence level, what size of sample is needed? Give your answer in whole people.

Question 8

Based on historical data in Oxnard college, we believe that 30% of freshmen do not visit their counselors regularly. For this year, you would like to obtain a new sample to estimate the proportiton of freshmen who do not visit their counselors regularly. You would like to be 95% confident that your estimate is within 1.5% of the true population proportion. How large of a sample size is required? Do not round mid-calculation.

Question 9

A political candidate has asked you to conduct a poll to determine what percentage of people support him. If the candidate only wants a 2% margin of error at a 99% confidence level, what size of sample is needed? When finding the z-value, round it to four decimal places.

Question 10

You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately 59%. You would like to be 90% confident that your estimate is within 2.5% of the true population proportion. How large of a sample size is required?

Question 11

A pollster wishes to estimate, with 95% confidence, the proportion of people who believe that recent changes in climate are primarily due to human activity.

Find the minimum sample size necessary to achieve a margin of error of less than 1%.

a. Assuming no previous estimates are available. Round your answer up to the next integer.

b. Assuming a previous estimate of 0.25. Round your answer up to the next integer.

Question 12

You want to obtain a sample to estimate a population proportion. Based on previous evidence, you
believe the population proportion is approximately 79%. You would like to be 90% confident that your
estimate is within 1.5% of the true population proportion. How large of a sample size is required? Do not
round mid-calculation.

Hint

StatisticsThe sample size is the term that is used to refer to the number of subjects, observations, or participants that are needed in order to carry out a specific survey. The sample size if often represented by the letter n. Sample sizes influence how accurate the estimates of our survey will be....

Students succeed in their courses by connecting and communicating with

an expert until they receive help on their questions

Consult our trusted tutors.