Question

1. A political candidate has asked you to conduct a poll to determine what percentage of people support her. If the candidate only wants a 7% margin of error at a 90% confidence level, what size of sample is needed?

2. You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately p = 0.14. You would like to be 99% confident that your estimate is within 2.5% of the true population proportion. How large of a sample size is required?

3. You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately 74%. You would like to be 90% confident that your estimate is within 3% of the true population proportion. How large of a sample size is required?

n = ____

4. You measure 23 watermelons' weights, and find they have a mean weight of 47 ounces. Assume the population standard deviation is 12.5 ounces. Based on this, what is the maximal margin of error associated with a 95% confidence interval for the true population mean watermelon weight.

Give your answer as a decimal, to two places

±________ ounces

5. You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=71.1σ=71.1. You would like to be 95% confident that your estimate is within 10 of the true population mean. How large of a sample size is required?

n = _____

Answer 1

1. Sample Size:

2.Sample Size:

3. Sample Size:

4.

Answers: (41.89, 52.11)

5.