In autumn of 2003, National Safe KidsCampaign performed study of helmet use among children ages 5 to 14 who participate in wheeled sports. Data were gathered from various sites acrossthe United States which were designated as places where children frequently engage in wheeled sports. Activity, apparent gender, and estimated age wererecorded for each rider, along with information on helmet use. It was found that, overall, 41% of children were wearing helmet while participating in awheeled sport. a. Was this study experiment or observational study? b. Recognize parameter of interest. c. Recognize statistic and give its value. d. Categorize four variables as numerical or attribute.