The National Sporting Goods Association (NSGA) conducted a survey of the ages of individuals that purchased skateboarding footwear. The ages of this survey are summarized in the following relative frequency distribution. Suppose the survey was based on a sample of 200 individuals. Age of User Percent Under 14 years old 35 14 to 17 years old 41 18 to 24 years old 15 25 to 34 years old 4 35 to 44 years old 4 45 to 64 years old 1 Calculate the mean, variance and standard deviation of the age of individuals that purchased skateboarding shoes. Use 10 as the midpoint of the first class. (Round your answers to 2 decimal places.)