What equations would help “capture” the coins? Extra credit

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)

You went to a restaurant and spent $53.25 on the meal. there was a 6% sales tax. what was the amount of money, not including a tip, you spent at the restaurant?

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?