Which problem can be solved using 3x7=21?

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?

Which number produces a rationale number when multiplied by 1/5

Askyscraper is 396 meters tall. at a certain time of day, it casts a shadow that is 332 meters long. at what angle is the sun above the horizon at that time?