Mr. Dion is the band director at school. He asks students to record how long they have played an instrument. The dot plot shows the data he has recorded. 2 dots on 1, 3 dots on 2, 4 dots on 3, 7 dots on 4, 1 dot on 5, 1 dot on 6. What unit of measure is used in the study. I need this asap.

Astudy was interested in determining if eating milk chocolate lowered someone's cholesterol levels. ten people's cholesterol was measured. then, each of these individuals were told to eat 100g of milk chocolate every day and to eat as they normally did. after two weeks, their cholesterol levels were measured again. is there evidence to support that their cholesterol levels went down? how should we write the alternative hypothesis? (mud = the population mean difference= before - after)a. ha: mud = 0b. ha: mud > 0c. ha: mud < 0d. ha: mud does not equal 0