You are interested in finding out whether middle-aged men who have premature heartbeats are at greater risk of developing a myocardial infarction (heart attack) than men whose heartbeats are regular. Electrocardiogram (ECG) examinations are performed on all male office employees 35 years of age or older who work for oil companies in Houston. The ECG tracings are classified as irregular or regular. Five years later, myocardial infarction rates are compared between those with and those without baseline ECG irregularities. What kind of study is this? a. Cross-sectional study
b. Case-control study
c. Prospective cohort study
d. Retrospective cohort study
e. Clinical trial
f. Community trial

The answer is "Option C".

Step-by-step explanation:

This study looks after results including such illness growth during the trial time, and this includes additional elements such as suspected risk or source of protection (s). The study usually consists of taking and looking at such a cohort of subjects for a long time. The main advantage of these studies is knowledge accumulation and higher efficiency. Systematic reviews may suffer from choice distortion, in addition to the potential indication misinterpretation.

in problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion. to find the cross products of a proportion, we multiply the outer terms, called the extremes, and the middle terms, called the means.

hope it

sinn is the total amount of students now and m were the students before, you subtract them both (n-m) and divide that by m. then, since to get a percentage from a fraction you have to multiply by 100, your answer should look like this: n-m/m*100

step-by-step explanation: