Worksheet 3 - Sample Size & Hypothesis Testing Student Name: Student ID: z Test for MeanZ Test for Proportion 1) A study is being conducted to compute the price of a hand cream. The researcher needs the error range of the price to be within $1, and suspects that the population standard deviation would be around $29. a. What sample size would we require if we desired a 99 percent confidence level? b. What about if we keep the confidence level 95%, but decide that our acceptable error is $4? 2) Suppose you are planning to sample transportation employees to determine average annual sick days. The following standards have been set: a confidence level of 99 percent and an error of fewer than 5 days. Past research has indicated the standard deviation should be 6 days. What is the required sample size? 3) A researcher expects the population proportion of FIFA fans in Abu Dhabi to be 80 percent. The researcher wishes to have an error of less than 5 percent and to be 98 percent confident of an estimate to be made from a mail survey. What sample size is required? 4) In a nationwide survey, a researcher expects that 30 percent of the population will agree with an attitude statement. She wishes to have less than 2 percent error and to be 90 percent confident. What sample size is needed? 5) The Al Ain Food and Beverages is one of the main supplier of bottled water in Al Ain. On average number of defected bottled is 220, with a standard deviation of 25. The confidence level is 95% and the Al Ain Food and Beverages had procured new machine and would like to statistically examine if the number of defects in production has changed because of the new machine. Worksheet 3 - Sample Size & Hypothesis Testing Student Name: Student ID: z Test for MeanZ Test for Proportion 1) A study is being conducted to compute the price of a hand cream. The researcher needs the error range of the price to be within $1, and suspects that the population standard deviation would be around $29. a. What sample size would we require if we desired a 99 percent confidence level? b. What about if we keep the confidence level 95%, but decide that our acceptable error is $4? 2) Suppose you are planning to sample transportation employees to determine average annual sick days. The following standards have been set: a confidence level of 99 percent and an error of fewer than 5 days. Past research has indicated the standard deviation should be 6 days. What is the required sample size? 3) A researcher expects the population proportion of FIFA fans in Abu Dhabi to be 80 percent. The researcher wishes to have an error of less than 5 percent and to be 98 percent confident of an estimate to be made from a mail survey. What sample size is required? 4) In a nationwide survey, a researcher expects that 30 percent of the population will agree with an attitude statement. She wishes to have less than 2 percent error and to be 90 percent confident. What sample size is needed? 5) The Al Ain Food and Beverages is one of the main supplier of bottled water in Al Ain. On average number of defected bottled is 220, with a standard deviation of 25. The confidence level is 95% and the Al Ain Food and Beverages had procured new machine and would like to statistically examine if the number of defects in production has changed because of the new machine
