In order to determine if living next to high-voltage power lines increases your chance of getting cancer, researchers selected several homes at random, determined if they were within 50 yards of a high-voltage power line, and recorded if anyone in the home had cancer. they compared the proportion of cancer cases in homes within 50 yards of a high-voltage power line with the proportion of cancer cases in homes more than 50 yards from a high-voltage power line. this is
a. an observational study
b. an experiment, but not a double -blind experiment
c. a matched pairs experiment

An observational study

Explanation:

observational studies are those a study  where the researcher observes the effect of a defy factor, diagnostic test, treatment or other intervention without trying to change who is or isn't exposed to it. Cohort study and control studies are of two observational studies. These are the part of fundamental of epidemiological research. These are called observational studies because the investigators observe individuals without manipulation and intervention. These studies are an important category of study design. Well, design observational studies maybe the next best method to address these types of questions.

answer: 42

use a calculator to find that 845/73 = 11.575

the whole part of the answer is 11. multiply this by 73 to get 11*73 = 803.

subtract that result from 845 to get 845 - 803 = 42