What’s the domain and range?

What is the exact volume of the cylinder (radius 13 in., height 30 in.)

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences. they randomly assigned 20 participants to a control group or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training. which statistical analysis should be performed to answer the researchers' question?

Julius sold five times as many computers as sam sold last year. in total, they sold 78 computers. how many computers did julius sell?