1. A population is estimated to have the standard deviation of 10. We want to estimate population mean in 2, with 95 percent level of confidence. How large a sample is needed?
2. A survey is being planned to find out the mean amount of time corporation executives watch television. A pilot survey indicated that the mean time for each week is 12 hours, with standard deviation of 3 hours. It is desired to estimate the mean viewing time in one-quarter hour. The 95 percent level of confidence is to be employed. How many executives must be surveyed?
3. Past surveys reveal that 30 percent of tourists going to Las Vegas to gamble throughout a weekend spend more than $ 1,000. The Las Vegas Area Chamber of Commerce wants to update this percentage.
- The new study is to employ the 90 percent confidence level. The estimate is to be in 1 percent of population proportion. What is the necessary sample size?
- Management said that the sample size determined above is too large. What can be done to reduce the sample? Based on your suggestion recalculate the sample size.