A study was performed in Basel, Switzerland, on relationship between the concentration of plasma antioxidant vitamins as well as cancer risk. Table shows data for plasma vitamin-A concentration for stomach cancer cases as well as controls.
Mean Standard Error n
Stomach-cancer cases 2.65 0.11 20
Controls 2.88 2421
b. Perform the appropriate test for question (a), and make a decision with the critical value at 0.05