1. In May, the mean price of gas in the Buffalo area was $2.714 per gallon with a standard deviation of $0.045. In a sample of 32 gas stations, what percentage will have a price per gallon of gas between $2.695 and $2.725?
2. A 2008 report on technology use states that approximately 28 percent of U.S. households have never sent an e-mail. Suppose that we select a random sample of 125 U.S. households, what is the probability that between 35 and 50 households have never sent email?
3. The attention span of a two year-old is normally distributed with a mean of about 9 minutes and a standard deviation of 1.75 minutes. Suppose we randomly survey 60 two year-olds. What is the probability that a two year old has an attention span of more than 8.5 minutes?