Consider these data on the selling prices ($000) of homes in the city of Warren, Pennsylvania, last year. 1. What is the class interval? 2. How many homes were sold last year? 3. How many homes sold for less than 210? 4. What is the relative frequency for the 210 up to 240 class?(结果用小数表示,并保留两位小数) 5. What is the midpoint of the 150 up to 180 class? 6. What was the maximum selling price? 7. What was the minimum selling price? 注:1-7的答案填写数字,如10,12.5