Suppose researchers were interested in determining the relationship, if any, between the use of cell phones and the incidence of brain cancer. Would it be better to use a randomized experiment, a case–control study, or an observational study that did not use cases and controls? Explain.

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3. be sure to show that you know the formula and how to plug into it. also, clearly state the margin of error.

Hii1977 cleaner shrimp are a species of shrimp that clean parasites from other organisms. fish allow the shrimp to eat the parasites in their mouth. the shrimp get a source of nutrition. the relationship between the shrimp and the fish is this association indicates that for the smaill aneser arecommensal, mutualistic, or parasitic for the begger one the anser are the shrimp and fish benefit each other , the shrimp harm the fish, or the fish do not benetit from the shrimp

What are the solutions of the system? solve by graphing. y = x^2 + 3x + 2 y = 2x + 2