Answer:
[tex](a)\ \frac{dP}{dt} = 0.078- 0.000857t[/tex]
[tex](b)\ P = 0.078t- 0.0004285t^2 + 7.02[/tex]
[tex](c)\ 9.37\ billion[/tex]
Step-by-step explanation:
Given
In 2012
[tex]P(t) = 7.02\ billion[/tex]
[tex]R_1 = 134\ million/year[/tex] --- Birth rate
[tex]R_2 = 56\ to\ 80[/tex] -- Death rate from '12 to '40
Solving (a): Equation for population from 2012
In 2012, we have the addition in population to be:
[tex]\triangle P= Birth - Death[/tex]
[tex]\triangle P= 134 - 56[/tex]
[tex]\triangle P = 78[/tex] million
From 2012 to 2040, we have the death rate per year to be:
[tex]Rate/yr = \frac{80 - 56}{2040 - 2012}[/tex]
[tex]Rate/yr = \frac{24}{28}[/tex]
[tex]Rate/yr = \frac{6}{7}[/tex] million/year
So, the differential equation is:
[tex]\frac{dP}{dt} = \triangle P - Rate/yr * t[/tex] where t represents time
[tex]\frac{dP}{dt} = 78 - \frac{6}{7} * t[/tex]
[tex]\frac{dP}{dt} = 78 - \frac{6t}{7}[/tex]
Express in millions
[tex]\frac{dP}{dt} = \frac{78}{1000} - \frac{6t}{7000}[/tex]
[tex]\frac{dP}{dt} = 0.078- 0.000857t[/tex]
Solving (b): The solution to the equation in (a)
[tex]\frac{dP}{dt} = 0.078- 0.000857t[/tex]
Make dP the subject
[tex]dP = (0.078- 0.000857t)dt[/tex]
Integrate both sides
[tex]\int dP = \int (0.078- 0.000857t)dt[/tex]
[tex]P = \int (0.078- 0.000857t)dt[/tex]
This gives:
[tex]P = 0.078t- \frac{0.000857t^2}{2} + c[/tex]
[tex]P = 0.078t- 0.0004285t^2 + c[/tex]
Solve for c.
When t = 0; P = 7.02
So, we have:
[tex]7.02 = 0.078*0- 0.0004285*0^2 + c[/tex]
[tex]7.02 =0-0 + c[/tex]
[tex]7.02 =c[/tex]
[tex]c = 7.02[/tex]
So:
[tex]P = 0.078t- 0.0004285t^2 + c[/tex]
[tex]P = 0.078t- 0.0004285t^2 + 7.02[/tex]
Solving (c): The population in 2050
We have:
[tex]P = 0.078t- 0.0004285t^2 + 7.02[/tex]
In 2050, the value of t is:
[tex]t = 2050 - 2012[/tex]
[tex]t = 38[/tex]
So, the expression becomes
[tex]P = 0.078*38- 0.0004285*38^2 + 7.02[/tex]
[tex]P \approx 9.37\ billion[/tex]
Create an algebraic expression to solve the following problems.
a) Jeff’s cell phone plan charges him $10 per GB with no extra fees. How much will his bill be for 6 GB?
b) Marks cell phone charges him $8 per GB and a monthly fee of $15 how much will his bill be for 10 GB
c) Ricks cell phone plan charges him $5 per GB and a monthly for of $30. How much will his bill be for 2 GB?
PLEASE ANSWER PLEASE
Answer:
Step-by-step explanation:
x is the number of GB
f(x) is the cost in dollars
f(x) = 10x
Bill for 6 GB = f(6) = 60
:::::
f(x) = 8x+15
Bill for 8 GB = f(10) = 95
:::::
f(x) = 5x+30
Bill for 2 GB = f(2) = 40
Anna charges $8.50 an hour to babysit how long will it take to make $51.00
Answer:
6 hours
Step-by-step explanation:
$51.00 ÷ $8.50 = 6 hours
hope this helps ! :))
Does anyone know this, scammers keep answering it
Answer:
Blank 1: 50
Blank 2: 95
Blank 3: is not
Blank 4: is not
Step-by-step explanation:
A right angle is 90 degrees, and a rectangle is a plane figure that has four straight sides and four right angles.
Omlll, I'm actually stuck rn xD If anyone can help,i'd appreciate it so much!! Tyssmm!!!!!
Answer: it’s acute
Step-by-step explanation:
the second one lollollol
help please grade 8 20 points and i need it
Answer
1) (4,6)
2) (5,5)
3) (2,6)
Step-by-step explanation:
PLEASE HELP!!!!!
Part A: Which person has earned more money after working 3 hours? Show or explain your work.
Part B: After how many hours of work Will Mary Ann and Carlos have saved the same amount?
show or explain your work.
Answer:
huh [•.•ิ] that's confusing sry
Answer:
after 3 hours they would each earn $21
Step-by-step explanation:
Select ALL TRUE statements about Linear Functions:
Group of answer choices
The degree of the function is one.
The y values change by a common difference.
The graph is a straight line.
Vertex form is used for graphing.
Step-by-step explanation:
The degree of the function is one: Correct
The y values change by a common difference: incorrect
The graph is a straight line: Correct
Vertex form is used for graphing: Incorrect
Hope that helps :)
Help?
The circumference of a circle is 25 cm. Find the length of the radius
Answer:
3.99
Step-by-step explanation:
Divide circumference by pi. The answer will be the circles diameter and then divide this by 2 for the radius
Unit 10: Circles ** please show how you got the answer ** i know the answer is 108° but i don’t know how to get it.
Answer:
108 degrees
Step-by-step explanation:
you gotta add the degrees up with a protractor or you add 54 plus 54 which equals 108
Please help with this question
Answer:
I think it's Democrats
Step-by-step explanation:
but I hope I am right
A rectangular billboard for a high school is 10 feet high and 20 feet long. In a scale model of the school, the billboard is 3.5 inches long.
How many inches tall is the scale model?
Answer:
I think 1.75
Step-by-step explanation:
the long side is two times the amount of the tall side so take the smaller long side and divide by two.
I have no clue how to do this! please help me!!!
Answer:
The equation has one solution.
A value of x that makes the equation true is 5, which when substituted into the equation and simplified makes the equation turn into 10=10
A value of x that makes the equation false is 6, which when substituted into the equation and simplified makes the equation turn into 12=10
Step-by-step explanation:
2x=10
Divide both sides by two:
2x/2=10/2
x=5. There is no other solution to the equation, because 5 is the only possible answer.
A spinner has six equal-sized sections numbered 1, 1, 2, 2, 3, and 4. What is the probability of spinning a 3?
Answer:
1/6 or 0.166666...
Step-by-step explanation:
1 out of 6, so 1/6
Find the equation (in terms of x) of the line through the points (-2,-4) and (2,8) y=
Answer:
y = 3x + 2
Step-by-step explanation:
What is a good estimate for this angle measurement? A. 10 degrees B. 25 degrees C. 75 degrees D. 95 degrees
Answer:
C. 75 degrees
Step-by-step explanation:
Answer:
75
Step-by-step explanation:
guys i guessed
If there are 2.54 centimeters in one inch, how many square centimeters are in one square inch? Hint: It is not 2.54! How is determining this conversion ratio related to linear and area scale factors for similar shapes?
Answer: It is related because linear scale factors are also squared for area scale factors.
Step-by-step explanation: Imagine two squares, which are similar (all squares are similar), and one has a side length of two and other has a side length of four. The length ratio is 1:2. But if you calculate the areas the area ratio is 1:4, which is the linear scale factor of two squared to get to 4
When creating equations for our word problems, we must remember to...
A. write all equations in slope-intercept form.
B. make sure all equations are in the same form.
C. define all variables.
9514 1404 393
Answer:
C. define all variables
Step-by-step explanation:
Equations for word problems will depend on the problem. Not all of the equations will be linear equations. Even if they are, they are not necessarily easily written in any particular form, or easily solved when they are written in that form. The nature of the equations will depend on the problem.
One thing that must be done in any case is define all variables. It is usually a good idea to define the units of the variable(s) as well. Sometimes problems are posed with numbers in incompatible dimensions, or they may ask for an answer in dimensions different from those used in the given information. In order to avoid confusion and to be sure you have the desired answer, you need to make sure the variables and their dimensions are compatible with the solution process.
If 10 is p percent of 21 , p is a number between
Answer: 47 and 48
Step-by-step explanation: 10/21 ≈0.476190476 and multiplied by a 100 to get a percentage is ≈ 47.6 which is in between 47 and 48. Hope this helps, and have a great day!
Answer: 47%
Step-by-step explanation:
half of 20 is 10 so half of 21 is 10.5
Help me with this pls
Answer:
x=65 degrees
Step-by-step explanation:
It's a right angle because a line is equal to 180* and one side is a right angle so the other is one as well so 90*-25*=65*
To find the distance between a point X and an inaccessible point , a line segment XY is constructed. Measurements show that XY = 975m , angle XYZ=22^ 42^ prime and angle YZX=105^ 18^ prime . Find the distance between X and Z to the nearest meter.
Answer:
sorry i didn't not answer
I need some help! I would really appreciate it!
Answer:
answer is A
Step-by-step explanation:
slope goes up positive 4 and it crosses the y intercept at 3 so yeg there ya go ig
Select all numbers that have and absolute value of 0.6
Help please !! need it adap
Answer:
m < Q = 40°
m < M = 60°
Step-by-step explanation:
1.) All angles in every triangle altogether equal 180°
From the 4 measurements, you can tell angle Q and S are equal in order to make all angles equal 180 and those angles to be equal (below)
180 - 100 = 80
80/2 = 40
2.) This is an isoceles (all angles and sides are equal) There are three angles (divide 180 by 3)
180/3 = 60
please answer i will give crown :D
Answer:
0.24
Step-by-step explanation:
1.679-1.439
Graph f(x) = 2 x + 3 + 2.
Answer:
HOPE IT'S HELPS YOU....Just want to confirm the answer is 4 more student because from 6 to 10 is 4
More or I’m wrong ?? Just please help me with yes or no thanks
Answer:
Yes
Step-by-step explanation:
Your answer is correct ^^
If x = 1 does x² - x = 0?
Answer:
Yes it does
Step-by-step explanation:
we would like to Prove the following for x=1:
[tex] \displaystyle {x}^{2} - x = 0[/tex]
since x=1 substitute:
[tex] \displaystyle {1}^{2} - 1 \stackrel {?}{=}0[/tex]
to simplify it we can consider the order of PEMDAS which is a abbreviation of
ParenthesesExponentMultiplication orDivision Addition orSubstractionsince exponent come first
simplify exponent:
[tex] \displaystyle {1}^{} - 1 \stackrel {?}{ = }0[/tex]
simplify substraction:
[tex]\displaystyle 0 \stackrel { \checkmark}{ = }0[/tex]
since left hand side equal to right hand side
hence, Proven
Alternate way:use a²-b²=(a+b)(a-b) to rewrite:
[tex] \displaystyle (x + \sqrt{x} )(x - \sqrt{x} ) = 0[/tex]
since x=1 substitute:
[tex] \displaystyle (1 + \sqrt{1} )( 1- \sqrt{1} ) \stackrel {?}{=} 0[/tex]
simplify square root:
[tex] \displaystyle (1 + 1)( 1- 1 ) \stackrel {?}{=} 0[/tex]
simplify parentheses:
[tex] \displaystyle (2)( 0) \stackrel {?}{=} 0[/tex]
Multiplying any number by 0 results 0 thus
[tex] \displaystyle 0 \stackrel { \checkmark}{=} 0[/tex]
since left hand side equal to right hand side
hence, Proven
Given,
x = 1
We need to find if x² - x = 0 is true or false.
If x = 1, then x² will be equal to 1² = 1 (1 multiplied by 1 is one / 1 square is equal to 1)
So,
=》x² - x = 0
By substituting ...
=》1² - 1 = 0
Now calculate...
=》1 - 1 = 0
=》0 = 0
•°• The given statement is true.
_____
RainbowSalt2222 ☔
Proving triangles similar
Answer:
x=11
Step-by-step explanation:
You do 38/3x+3 and 19/x+7 and then cross mulitply and get 57x+57=38x+266. Then yoy subtract 57 from 266 and get 57x=38x+209. Now you have to subtract 38 from 57 and then answer will be 19. So now you have 19x=209. Finally you divide 209 by 19 and get x=11. Good luck!
17.
Which pair of numbers is relatively prime? *
7 & 21
4 & 15
ОООО
6 & 9
9 & 27
Answer:
9 & 27
Step-by-step explanation:
since all prime numbers above 5 end in 1,3,7 and 9then to find a prime number between say 70 and 80 the only possibilities are 71,73,77,79
Answer:
9 & 27
Step-by-step explanation:
Plz mark as Brainliest...
3.65 is greater than or less than 3and1/5
Answer:
Greater
Step-by-step explanation:
It is greater because 3 & 1/5 is technically 3.20 which obviously results with 3.65 being greater than 3.2. Also if you go into detail with it 3.65 is kinda 3 & 3/5. Thanks. Let me know if you find any fault in my answer. Have a good day!
