Statistics problems

Based on a simple random sample of one hundred an analyst estimates the average hourly wage earned by workers in a city to be $30 and computes the margin of error to be $5. Can we conclude from this that most workers there earn between $25 and $35 per hour? Is the right interpretation for the margin of error? Polls showed the two main candidates in the 2004 presidential election were nearly tied on the day before the election. To predict the winner a newspaper would like to have a poll that has margin of error of less than 1%. Roughly how large a sample would be needed for such a poll? Chapter 8 6. A large population of overdue…

Inferences for One Population Standard Deviation

The Standard deviation is a measure of the variation (or spread) of a data set. For a variable x, the standard deviation of all possible observations for the entire population is called the population standard deviation or standard deviation of the variable x. It is denoted σx or, when no confusion will arise, simply σ. Suppose that we want to obtain information about a population standard deviation. If the population is small, we can often determine σ exactly by first taking a census and then computing σ from the population data. However, if the population is large, which is usually the case, a census is generally not feasible, and we must use inferential methods to obtain the required information about…