The initial population is
P₀ = 94 million in 1993
The growth formula is

where P(t) is the population (in millions) after t years, measured from 1993.
k = constant.
Because P(5) = 99 million (in 1999),

In the year 2005, t = 12 years, and

Answer: 106 million (nearest million)
The total population of the town is 2270 people.
First of all, this is not an observational study, but an experiment, since we have two groups and one of the two groups is manipulated or treated. In an observational study the subjects are only observed.
Second, the students did not choose their groups - so we can't choose the last answer.
Therefore the correct answer is:
This is an experiment because a treatment was applied to a group.