The birth rate in a certain city is described by the following function b(t)=5.48 -0.01 t^2. The city's death rate is given by d(t)=5+0.02 t^2. Here, t is measured in years, and t = 0 corresponds to the start of the year 1990. The birth and death rates are measured in thousands of births or deaths per year. At the start of 1990, the population of the city is 150 thousand. Enter all the following answers correct to two decimal places.

Calculate the total number of births between the start of 1990 and the end of 1999. Number of births = thousand.
Calculate the total number of deaths over the same period Number of deaths = thousand.
What is the population of the city at the start of year 2000? Population : thousand.
Considering just the period from the start of 1990 to the start of 2000, over what interval is the population increasing? (Enter your dates as years, not the number of years since 1990.)
Over what interval is the population decreasing?
Calculate the area between the curves y = b ( t ) and y = d ( t ) for t between 0 and 10. Area :

1. 4,67 thousand

2. 6,62 thousand

3. 148,05 thousand

4. The population increases from 1991 to 1994, and decreases from 1995 to 1999

5. Area between the curves:

y=b(t)=51,47

y=d(t)=56,67

Step-by-step explanation:

1.Total number of births in 1999. Evaluating the function b(t) at t=1999-1990=9

2. Total number of births in 1999. Evaluating the function d(t) at t=1999-1990=9

3. The equation that calculate the population of the city in certain period of time is:

In this case, the population at the star of the year 2000 could be calculate by evaluating the function at t=9. Then, replacing the results of b(9) and d(9):

4. Evaluate the function at t=0,1,2,...,9 (See the attachment)

The values show that the population increases during 1991 and 1994, and decreases during 1995 and 1999.

5. Calculating the area between the curves requires to calculate the integrated and evaluated at the interval given:

For y=b(t):

Evaluating the function at t=0 and t=10:

Evaluating the function at t=0 and t=10:

b) the dogs need to shift their focus to human scent.

step-by-step explanation: it is d