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.
Answer:
Step-by-step explanation:
The population of a community is known to increase at a rate proportional to the number of people present at time t.
This means that the population growth is modeled by the following differential equation:
Which has the following solution:
In which P(t) is the population after t years, P(0) is the initial population and r is the growth rate.
The population has doubled in 10 years
This means that 
. We use this to find r.
So the equation that will estimate the population of the community in t years is:
Answer:
Eric has 4 quarters
Step-by-step explanation:
31-7=24
24/6=4
Answer:
3x + 4
Step-by-step explanation:
2x + 1x + 4 =
(2x + 1x) + 4 =
3x + 4
<em>Hope that helps!</em>
Answer:
39
Step-by-step explanation:
median is the middle number
12, 21, 21, 23, 34, 34, 34, 44, 45, 56, 72, 86, 97, 98
34-44=10
10/2=5
34+5=39
39
