a sales team estimates that the number of a new phones they will sell is a function of the price that they set. they estimate that if they set the price at x dollars, they will sell f(x)=1720-5x phones. therefor the company’s revenue is x•(1720-5x). find the price x which will maximize the company’s revenue

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?