What is a case-control study?

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

Astore has apples on sale for three dollars or 2 pounds how many pounds of apples can you buy for nine dollars if an apple is approximately 5 ounces how many apples can you buy for nine dollars

For g(x) = 5x - 3 and h(x) = [tex]\sqrt{x}[/tex], find (g · h)(4)