Exam 9: Introduction to Estimation

An engineer for an electric fencing company is interested in the mean length of wires being cut automatically by machine. The desired length of the wires is 12 feet. It is known that the standard deviation in the cutting length is 0.15 feet. Suppose the engineer decided to estimate the mean length to within 0.025 with 99% confidence. What sample size would be needed?

If we have some idea about the value of sample proportion , we use that value in determining the sample size needed to estimate the population proportion p.

Socialist Party Voters: A pollster in Italy wants to challenge a claim that 5% of the registered voters in his country are Socialists; he thinks the percentage is lower than that. In a test of hypothesis, H₀: p = 0.05 vs. H₁: p < 0.05, his random sample of size 1,000 registered voters revealed that the number of Socialists was 40. -{Compute the p-value and explain how to use it to test the hypotheses.

The sample ____________________ is relatively more efficient than the sample ____________________ when estimating the population mean.

A point estimate consists of a single sample statistic that is used to estimate the true population parameter.