In a study conducted at the University of Chicago, S. Frankel and colleagues studied middle school students in 10 Illinois communities. Each year for 7 years, they measured the lung function of the children and the levels of coal ash particles in the air in the communities. Was this a cohort study or a case-control study? Was the study prospective, cross-sectional, or retrospective? Pick from the following:
A). This was a retrospective cohort study
B). This was a prospective case-control study
C). This was a retrospective case-control study
D). This was a cross-sectional cohort study
E). This was a prospective cohort study

D). This was a cross-sectional cohort study

Step-by-step explanation:

The given situation is an example of cross sectional cohort study because the investigator choose the samples from the population using cross sectional method and use the same sample source for analyzing the independent variables for specific period of time or intervals of time to assess the history of exposures and outcomes.

Here, the lung function is tested at an interval of 7 years compared with the levels of exposure to the coal ash so it is the example of cross sectional cohort study.

rounding to the nearest thousandth would be 452,000

3/4 ÷ 3/4

step-by-step explanation:

basically divide any proper fraction with itself to fit the criteria.

so if we are using 3/4, then:

3/4 ÷ 3/4 = 1

so 1 is the quotient.

and the numerators for both these fractions is 3.   and if we divide the numerators:

3 ÷ 3 = 1

we see that quotient is equal to our original quotient as well.