Answer:
The correct answer is - an observational study.
Step-by-step explanation:
It is given that, Researchers periodically survey a few thousand of the patients. These are taking specific medicine patients and researchers taking this survey to find the connection between that medication and the subjects' general health.
So, it can say that the researchers observed the patient's health by the effect of the medication, therefore, the Observational Study is the given method of gathering data.
Answer:

Step-by-step explanation:
Answer:
50 mph
Step-by-step explanation:
To calculate averages you add up all the items and divide by the total number of items there is.In this problem were 2 items so you divide it by 2
Add the two numbers
40+60=100
now just divide by 2 because there was 2 drives giving you 50 mph
Hope this helps!
:)