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 answers to 2 decimal places.