# Question: Referring to the previous problem you often hear the results

Referring to the previous problem, you often hear the results of such a poll in the news. In fact, the newscasters usually report something such as, “44.9% of the population approve or strongly approve of the President’s handling of the environment. The margin of error in this result is plus or minus 3%.” Where does this 3% comes from? If the pollsters want the margin of error to be plus or minus 3%, how does this lead to a sample size of approximately 1000?

## Answer to relevant Questions

The widths of 100 elevator rails have been measured. The sample mean and standard deviation of the elevator rails are 2.05 inches and 0.01 inch. a. Find a 95% confidence interval for the average width of an elevator rail. Do ...We know that IQs are normally distributed with a mean of 100 and standard deviation of 15. Suppose you want to verify this, so you take 100 random samples of size four each and, for each sample, find a 95% confidence ...Find a 95% confidence interval for the difference between the mean cost per item for female orders and the similar mean for males.SoftBus believes it can afford to spend much less time with customers who own PCs and score at least 4 on PCKnowledge. Let’s call these the “PC-savvy” customers. On the other hand, SoftBus believes it will have to ...The formula for a 95% confidence interval for a mean is so well-rooted in statistical theory and practice that you might not even consider other possibilities. However, many researchers and even practitioners favor a totally ...Post your question