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]
Kelly had an apple She cut it in half, and then she cut it in half again
She ate three pieces of the apple. How many pieces did Kelly have it?
Step-by-step explanation:
I think the answer is 3 pieces so Kelly had 3 pieces of Apple hope it helps.
Find AB. Round the answer to the nearest tenth if needed.
9514 1404 393
Answer:
8
Step-by-step explanation:
The product of segment lengths to the near and far circle intersection points is the same for both "secants". AD is a tangent, so the two intersection points are the same point. This gives ...
AD² = AB·AC
144 = AB(AB +10)
We can add 25 to complete the square.
169 = (AB +5)² . . . write as a square
13 = AB +5 . . . . . . positive square root
8 = AB . . . . . . . . . .subtract 5
Which expression is equivalent to 8x - 12y + 32
Answer:
C
-16(0.5x-0.75y+2)
Step-by-step explanation:
I got it right on edge 2022 Hope it helps <3
Solve for x
Plz help!
Margot has paid $13,800 in
rent for a year. How much is
her monthly rent, r?
Hint: Remember there are 12
months in a year.
Answer:
$1150 per month
Step-by-step explanation:
13800/ 12
Two Social Security numbers (see Exercise 8.12) match zeros if a digit of one number is zero iff the corresponding digit of the other is also zero. In other words, the zeros in the two numbers appear in exactly the same position. For example, the Social Security numbers 120-90-1109 and 430-20-5402 have matching zeros.
Prove: Given a collection of 513 Social Security numbers, there must be two that match zeros.
Answer:
Proved
Step-by-step explanation:
From the given parameters, we have:
[tex]n = 9[/tex] i.e. the length of each security numbers
[tex]r = 2[/tex] i.e. 2 security numbers
Required
In 513 security numbers, 2 must have matching zeros
To do this, we make use of Pigeonhole principle.
First, we calculate the number of all security numbers not having matching zeros.
Each of the 9 digits can be selected in 2 ways.
2 ways implies that each digit is either 0 or not
So, total selection is:
[tex]Total = 2^9[/tex]
[tex]Total = 512[/tex]
Apply Pigeonhole principle
The principle states that: suppose there are n items in m containers, where [tex]n>m[/tex], then there is at least one container that contains more than 1 item.
This means that if there are 512 security number without matching zeros, then there is 1 (i.e. 512 + 1) with matching zeros.
[tex]512 + 1 = 513[/tex]
Which equation shows x^2+6x-2 = 0 rewritten by completing the square?
A. (x+3)^2=18
B. (x+3)^2-11
C. (x+3)^2-2
D. (X+3)^2-9
Answer:
Option B.
Step-by-step explanation:
We have the equation:
x^2 + 6*x - 2 = 0
Remember that:
(a*x + b)^2 = (a*x)^2 + 2*a*b*x + b^2
Because the term with x^2 has a coefficient equal to 1, then a = 1.
(x + b)^2 = x^2 + 2*b*x + b^2
The ter with x is: 6*x
then:
2*b*x = 6*X
2*b = 6
b = 6/2 = 3
we have:
(x + 3)^2 = x^2 + 6*x + 9
Now, our equation is:
x^2 + 6*x - 2 = 0
Now we can add the term (11 - 11) = 0
x^2 + 6*x - 2 + (11 - 11) = 0
x^2 + 6*x - 2 + 11 - 11 = 0
x^2 + 6*x + (11 - 2) - 11 = 0
x^2 + 6*x + 9 - 11 = 0
And we know that:
x^2 + 6*x + 9 = (x + 3)^2
Then we can rewrite our equation as:
(x + 3)^2 - 11 = 0
Then the correct option is B.
The equation that matches our result is option B. (x+3)² - 11. Therefore, rewriting x² + 6x - 2 = 0 by completing the square gives us (x+3)² - 11 = 0.
To rewrite the equation x² + 6x - 2 = 0 by completing the square, we need to follow these steps:
Move the constant term (-2) to the other side of the equation:
x² + 6x = 2
Take half of the coefficient of x (which is 6) and square it. Add the result to both sides of the equation:
x² + 6x + (6/2)² = 2 + (6/2)²
x² + 6x + 9 = 2 + 9
x² + 6x + 9 = 11
Now, let's look at the answer choices:
A. (x+3)² = 18
B. (x+3)² - 11
C. (x+3)² - 2
D. (x+3)² - 9
Among the answer choices, the equation that matches our result is option B. (x+3)² - 11. Therefore, rewriting x² + 6x - 2 = 0 by completing the square gives us (x+3)² - 11 = 0.
To know more about equation:
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what is a good communication
Answer:
text or video calls
Step-by-step explanation:
Answer: Employers value employees who can communicate effectively;
Step-by-step explanation: it means they are able to listen to others, as well as successfully relay their own ideas and opinions.
A computer engineer is investigating whether the amount of installed RAM (random access memory) can be used to predict the mean cost of a laptop with the operating system. The computer engineer collected a sample of 20 laptops with the same operating system. The engineer wants to estimate the mean change in the cost, in dollars, for each increase of 1 gigabyte of installed RAM. Assuming the conditions for inference have been met, which of the following inference procedures is the most appropriate for such an investigation?
a. A two-sample z-interval for a difference between proportions.
b. A two-sample t-interval for a difference between means.
c. A matched-pairs t-interval for a mean difference.
d. A one-sample t-test for means.
e. A linear regression t-interval for slope
Find the mean absolute deviation for the set below. S = 65, 90, 85, 70, 70, 95, 55
A. 12.24
B. 75.7
C. 114
D. 32.67
(I’ll give points + brainalist)
Answer:
A) 12.24
Step-by-step explanation:
Mean absolute deviation: 65, 90, 85, 70, 70, 95, 55 = 12.244897959184
Answer:
75.7
Step-by-step explanation:
Noah has 102 inches of border for poster board. He uses 7 feet of the border. How much border is left
Answer:
The answer is 18.
Step-by-step explanation:
You take 7x12 which is 84 and then you take 84 and subtract it from 102 inches so 102-84=18.
Hope this helps!
Noah after using 7 feet of the border is now left with 95 feet of the boarder.
What are some alternative names for arithmetic operations?Addition is also known as the sum, subtraction is also known as the difference, multiplication is also known as the product, and division is also known as the factor.
We also know about some basic properties of arithmetics,
There are three types of basic arithmetic laws of operation.
Commutative law for addition and multiplication states,
a + b = b + a.
a×b = b×a.
Distributive law states,
a(b ± c) = ab ± ac.
Associative law states,
a + (b + c) = (a + b) + c.
Given, Noah has 102 inches of the border for poster board and he uses 7 feet of the border.
Therefore, The amount of border left can be obtained by subtracting the length used from the total length which is,
= (102 - 7) feet.
= 95 feet.
learn more about arithmetic operations here :
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When eleven is reduced by one-third of a number, the result is 5
. Find the number.
Answer:
18
Step-by-step explanation:
11 - 1/3x = 5
Subtract 11 from both sides
-1/3x = -6
Multiply both sides by -3
x = 18
14.53 less then or greater then 16.3
Answer:
14.53 is less than 16.3, that is the answer
Answer:
14.53 is less than 16.3
yes this is mathematics
whats 21(2 - m) + 12m = 44. please
Answer:
= − 2 /9
Step-by-step explanation:
Complete the sentence.
9 is 36% of
Answer:
35
Step-by-step explanation:
[tex]\frac{9}{y} =\frac{36}{100}[/tex]
y × 36 = 9 × 100
36y = 900
36y ÷ 36 = 900 ÷ 36
y = 35
Answer:
25
Step-by-step explanation:
36% 9
-------------- (36% over 100% and 9 over x)
100% x
Cross multiply: 36% times x and 100% times 9
36% times x=36x
100% times 9=900
Divide: 900 divided by 36=25
25 is your answer
Hope this helped!
Bella was here :)
HELP LOOK AT PHOTO PLEASE
Answer:
y=60
Step-by-step explanation:
1) Find x
All the interior angles of a triangle add up to 180 degrees. Knowing this, we can construct the following equation:
[tex]180=x+35+25\\180=x+60[/tex]
Subtract 60 from both sides
[tex]180-60=x+60-60\\120=x[/tex]
2) Find y
A straight line has an angle measure of 180 degrees as well. Knowing this, we can construct the following equation:
[tex]180=x+y\\180=120+y[/tex]
Subtract 120 from both sides of the equation
[tex]180-120=y+120-120\\60=y[/tex]
There is also a second way to solve for y: An exterior angle of a triangle is equal to the sum of the opposite interior angles. y, in this case, would be the exterior angle and 35 and 25 degrees would measure the opposite interior angles. To solve for y, we just add 35 and 25, getting us 60 degrees.
I hope this helps!
Help please!
This is due on April 18th but I would prefer the answer today! No sus links please!
3(y-2)=18
3y-6=18
3y=24
y=8
HOPE THIS HELPS AND YOU GOT GOOD GRADES
Answer:
blank 1= 6
blank 2=6
Step-by-step explanation:
y=2
3y=6
6/3=2
hope that helps
have a great day/night
A certain high school reported that only 74% of its students enroll in a math class during senior year. If
there are 407 seniors enrolled in math at this school, how many seniors are in the school?
Answer:
550 students are in the school.
Step-by-step explanation:
The way I found my answer was by first turning 74% into a decimal, which is 0.74. Then I divided 407 by 0.74 and I got 550. Therefore, 550 is our answer.
Hayden has 90 trading cards
Answer:
9
Step-by-step explanation:
90/10 =9
The eight subjects used for this comparison were not a random sample. In fact, they were friends of the researchers whose ages and weights were similar to the types of people who would be measured with this DXA. Comment on the appropriateness of this procedure for selecting a sample, and discuss any consequences regarding the interpretation of the significance testing and confidence interval results.
Answer:
The sample may be a representative of the future of the future subjects, but the test results and confidence interval are suspect because it is not a random sample
Step-by-step explanation:
When the subjects used for a research are not a random sample but friends whom share similar qualities/quantities related to the purpose of the experiment. The sample may be a representative of the future subjects, but the test results and confidence interval will not be reliable enough to be accepted as standard simply because it was not a random sample
Hence the comment :The sample may be a representative of the future of the future subjects, but the test results and confidence interval are suspect because it is not a random sample
Special right triangles. find the value of x?
hypotenuse = leg ×
[tex] \sqrt{2} [/tex]
Answer:
x = (9√2)/2
Step-by-step explanation:
Reference angle = 45°
Hypotenuse length = 9
Adjacent length = x
Apply the trigonometric ratio CAH:
Cos 45° = Adj/Hyp
Cos 45° = x/9
Multiply both sides by 9
9*Cos 45 = x
9*1/√2 = x (cos 45 = 1/√2)
9/√2 = x
Rationalize
(9*√2)/2 = x
x = (9√2)/2
find the gcf of 2³×3² and 2³×3⁴ please no links
Answer:
Step-by-step explanation:
GCF - List out the prime factors that are common to both numbers
2³ * 3²
2³ * 3⁴
GCF = 2³ * 3² = 8 *9 = 72
ZABD and ZDBC are supplementary angles.
What is the measure of x?
x = [?]°
7D
AK
X78°
B
>C
Angles are not drawn to scale.
Enter
Will give Brainiest if right
Answer:
79*
Step-by-step explanation:
3000, 300, 30, 3, ...
O Arithmetic
O Geometric
O Neither
Answer:
code answer :unknown 976765 answer .geometric
please answer asap! no scam links or scam comments or reported.
Answer:
C
Step-by-step explanation:
Answer:
B. The longer a skydiver is in freefall, the more feet they fall per second
Step-by-step explanation:
You have 32 cups of milk. You need 1.25 cups to make one serving of deep-fried chicken. How many servings can you make? Whole servings only - round down rather than using partial servings.
Answer:
25 cups and 3/5 of a cup
Step-by-step explanation:
Bro trust me
Answer:
25
Step-by-step explanation:
32÷1.25=25.6
I hope this helps ^-^
Find the common ratio of the geometric sequence. You must write r=
7640, 764, 76.4, 7.64,
Answer:
1/10 is the common ratio
simplified is 0.1
mark me brainilest:)
At the book fair, Vald spends all of his money on new books. Pamela spends
2/3 as much as Vald. Eli spends 4/3 as much as Vald. Who spent the most?
The least?
Step-by-step explanation:
Lets take Vald spends $100 on the book fair which are all the money he had.
Pamela Spends 2/3 as much as Vald
Pamela Spends 2/3 x 100 = $66.67
Eli Spends 4/3 as much as Vald
Eli spends 4/3 x 100 = $133.33
From here, we can see Eli Spends the most and Pamela Spends the least.
A resort hotel rents
bicycles for $20 plus an hourly rate of $6. A
nearby hotel rents bicycles for $15 plus an hourly
rate of $8.
Which equation can be used to determine h, the
number of hours it will take for the cost of renting
a bicycle at both hotels to be the same?
Answer:
the answer is 20+6h=15+8h
Help please will mark brainliest!!!
Answer:
504
Step-by-step explanation:
A = (.5bh)*6
Plug in your known numbers
A = (.5*12*14)*6
Since there is nothing missing just multiple together and you'll get