Help please with differential equations and their applications (1/2) i don't understand the concept at all and have an exam coming up

The CIA published data about foreign countries on its web page. In particular they show total population as well as population growth. If a student is looking at Russia. they will see that the total population of Russia is declining. When they look at the table that shows annual population growth all the rates are positive. Assume population grows and declines at a rate proportional to the population. What is the problem? I Question 19 (3 points) Question 17 (3 points) A city block has 10 pigeons and then 1 week later there are 15 pigeons. Assuming the rate of growth is proportional to the number of pigeons present, what is the differential equation which describes the growth of the pigeon population? Solve this equation to find the equation that describes how many pigeons are present. Let P(t) be the number of pigeons where t is measured in weeks. I Question 18 (3 points) Jane is taking a history class. The teacher states that the population of a country is shrinking at a rate proportional to the population at a given time, and describes the size of the population as P = 10e SUP 0.5t SUP , where t is years. Is this possible? i l Question 16 (3 points) If an object's mass is changing at a rate proportional to its weight at a given time, does it make sense to use differential equations to model the weight, W, of the object? Question 21 (3 points) If a population of fruit flies triples every 6 days. What is k, the proportionality constant