7.45 Of all individual tax returns filed in the United States during the 2009 tax filing season, 15.8% were prepared by H&R Block. For a randomly selected sample of 900 tax returns filed during this period, use the normal approximation to the binomial distribution in determining the probability that between 110 and 140 of these returns were prepared by H&R Block. Source: hrblock.com, July 14, 2009.