Hi there!
a.
To find the total amount of people that have ENTERED by t = 20, we must take the integral of the appropriate function.

Evaluate using a calculator:

b.
To solve, we can find the total amount of people that have entered of the interval and subtract the total amount of people that have left from this value.
In other terms:

We can evaluate using a calculator (math-9 on T1-84):


c.
If:

Then:

Evaluate at t = 20:


This means that at t = 20, there is a <u>NET DECREASE</u> of people at the movie theater of around 20.823 (21) people per hour.
d.
To find the maximum, we must use the first-derivative test.
Set S(t) - R(t) equal to 0:

Graph the function with a graphing calculator and set the function equal to y = 0:
According to the graph, the graph of the first derivative changes from POSITIVE to NEGATIVE at t ≈ 17.78 hours, so there is a MAXIMUM at this value.
<u>Thus, at t = 17.78 hours, the amount of people at the movie theater is a MAXIMUM.</u>
They are used as radio waves, infrared radiation, visible light.
<h3><u>Answer;</u></h3>
The above statement is True
The energy in fossil fuels is derived from the energy stored in plant and animal matter.
<h3><u>Explanation;</u></h3>
- Fossil fuels are sources of energy that have developed within the earth over millions of years. Because fossil fuels - oil, natural gas, and coal - take so long to form, they are considered nonrenewable.
- Fossil fuels are a great source of energy because they originate from living things. Plants and trees use sunlight to make food from carbon dioxide and water, using the process called photosynthesis. The energy from the sun gets stored in the plants and transferred to any animal that eats the plants.
Answer:
Freezing
Explanation:
Hope it helps you........
Answer:
The children are experiencing natural reinforcement.
Explanation:
Sandra's children are very successful in school and that is a stated natural reinforcer.
Natural reinforces occur as a result of their behavior without involving others expressing their approval of their behavior.
Sandra is trying to foster this natural reinforcement with positive social reinforcement, "but she does not always remember".