Laura Strubel is reviewing some data from a marketing research report she obtained that shows the age of persons who frequently purchase her company's product, Strubel's Gourmet Seafood frozen dinners. Laura is considering buying radio time for a new ad campaign, and knowing the age of the target market would be very helpful to her in selecting which stations should run the ads. Laura sees that the mean age of frequent buyers is 45 with a standard deviation of 12. She correctly interprets this to mean that 68 percent of her target market fall between the ages of: 39 to 51 45 to 68 33 to 57 33 to 56 45 to 57