A city planner is investigating traffic congestion at a certain intersection. To collect data, a camera will record the number of cars that pass through
the intersection at different hours of the day and on different days of the week.
Which of the following best
describes the type of investigation being conducted by the city planner?
(A) The investigation is an experiment because the cars go through the intersection at random.
(B) The investigation is an experiment because the hours and the days are the treatments and the cars are the
units.
(C) The investigation is an observational study because treatments are not imposed.
(D)
The investigation is an observational study because only a sample of cars can go through the intersection on
any given day.
(E)
The investigation is a sample survey because the cars that are recorded will inform the city planner about the
population of cars on city roads.