elijah1090

17.04.2020 • 

Mathematics

Many studies have found that people who drink alcohol in moderation have lower risk of heart attacks than either nondrinkers or heavy drinkers. Does alcohol consumption also improve survival after a heart attack? One study followed 1913 people who were hospitalized after severe heart attacks. In the year before their heart attacks, 47% of these people did not drink, 36% drank moderately, and 17% drank heavily. After four years, fewer of the moderate drinkers had died. (a) What type of study is this? Observational study: prospective Observational study: retrospective Observational study: cross-sectional Experiment: matched pairs design Experiment: randomized block design Experiment: completely randomized design (b) What population or populations are represented in the study? all individuals who drink alcohol all heavy drinkers and all nondrinkers all individuals who have suffered a severe heart attack all individuals who drink and have been hospitalized (c) What is the explanatory variable? time until a heart attack alcohol consumption level (none, moderate, heavy) number of heart attacks death (yes, no) (d) What is the response variable? time until a heart attack number of heart attacks alcohol consumption level (none, moderate, heavy) death (yes, no)

Ответ:

AnastasiaJauregui

23.02.2023

Mathematics

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Permutation is a mathematical operation that is concerned about the ordered of the elements. The word "helicopter" has 10 elements or letters. Only 2 e's are repeated. Hence, the permutation is equal to 10! / 2!. The numerical value of this is equal to 1814400. The answer is letter B. 

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