Which equation would best solve the following problem?

rita hits a tennis ball with an initial velocity of 15 meters/sec. when she hits the ball, it is one meter above the ground. how long will it take for the ball to hit the ground?
question 1 options:

–16t^2+ 15t + 1 = 0

–4.9t^2 + 15t = 1

–4.9t^2 + 15t + 1 = 0

4.9t^2 + 15t + 1 = 0

Stu and ambrose are working together on a study of whether diet is related to students' mental health. first, they randomly select 10 students from the student center and 10 students from the office of counseling and psychological services. then, they ask students to rate their diet in terms of healthiness on a scale of 1-100 before completing a 20-item mental health survey. a) name one of the constructs being studied b) how was the construct you named above operationally defined in this experiment? e) was the variable you described above their independent variable, their dependent variable, or a controlled variable? d) what is a confounding variable? what is a potential confound in this study?