A tank contains 9,000 L of brine with 18 kg of dissolved salt. Pure water enters the tank at a rate of 90 L/min. The solution is kept thoroughly mixed and drains from the tank at the same rate.
(a) How much salt is in the tank after t minutes?
(b) How much salt is in the tank after 20 minutes?

Answers

Answer 1

Let x(t) denote the amount of salt (in kg) in the tank at time t. The tank starts with 18 kg of salt, so x (0) = 18.

The solution is drained from the tank at a rate of 90 L/min, so that the amount of salt in the tank changes according to the differential equation

dx(t)/dt = - (x(t) kg)/(9000 L) × (90 L/min) = -1/100 x(t) kg/min

or, more succintly,

x' = -1/100 x

This equation is separable as

dx/x = -1/100 dt

Integrating both sides gives

∫ dx/x = -1/100 ∫ dt

ln|x| = -1/100 t + C

x = exp(-1/100 t + C )

x = C exp(-t/100)

(a) Using the initial condition x (0) = 18, we find

18 = C exp(0)   ==>   C = 18

so that

x(t) = 18 exp(-t/100)

(b) After 20 minutes, we have

x (20) = 18 exp(-20/100) = 18 exp(-1/5) ≈ 14.74

so the tank contains approximately 14.74 kg of salt after this time.


Related Questions

What is the value of the expression, written in standard form?

Answers

Answer:

200

Step-by-step explanation:

6.6/3.3 = 2

10^-2 - (-4) = 10^2

The answer is 2 * 10^2 or 200.

Which of the following is equivalent to 0 equals 3 x squared minus 12 x minus 15 when completing the square?

Answers

Answer:

x = 5, -1

Step-by-step explanation:

0 = 3x^2 - 12x - 15 or

3x^2 - 12x - 15 = 0

By solving for x, use the Quadratic Formula.

… x = 5 and/or -1

After completing the square the quadratic equation [tex]3x^{2} -12x-15=0[/tex] is equivalent to [tex](x-2)^2=3^2[/tex].

What is a quadratic equation?

"It is a polynomial equation with degree two."

What is completing the square method?

"It is a method that is used for converting a quadratic expression of the form [tex]ax^2 + bx + c[/tex] to [tex]a(x - h)^2 + k[/tex] "

For given example,

We have been given a quadratic equation.

[tex]3x^{2} -12x-15=0[/tex]

First we divide above quadratic equation by 3,

[tex]x^{2} -4x-5=0\\\\x^2-4x=5[/tex]                             ................(i)

Now for completing the square first find [tex](\frac{-b}{2a} )[/tex]

[tex]\frac{-b}{2a}\\=\frac{-(-4)}{(2)(1)}\\\\ =\frac{4}{2}\\\\ =2[/tex]

Add [tex](\frac{-b}{2a} )^2[/tex] on both the sides of equation (i),

[tex]x^{2} -4x+4=5+4\\\\(x-2)^2=9\\\\(x-2)^2=3^2[/tex]

Therefore, after completing the square the quadratic equation [tex]3x^{2} -12x-15=0[/tex] is equivalent to [tex](x-2)^2=3^2[/tex].

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[tex] \frac{2}{4} + 5 \times 36 + 2 \frac{6}{3 } = [/tex]
what is answer ​

Answers

Step-by-step explanation:

[tex] \frac{2}{4} + 5 \times 36 + 2 \frac{6}{3} [/tex]

[tex] = \frac{1}{2} + 180 + 2 \times \frac{2}{1} [/tex]

[tex] = \frac{1}{2} + 180 + 4[/tex]

[tex] = \frac{1 + 360 + 8}{2} [/tex]

[tex] = \frac{369}{2} [/tex]

[tex] = 184 \frac{1}{2} \: or \: 184.5(ans)[/tex]

Find the lengths of the other two sides of the isosceles right triangle

Answers

Answer:

h²=p²+b²

(7√2)²=x²+x²

(49×2)=2x²

2x²=49ײ

x²=49×2/2

x²=49

x=√49=7

x=7

OAmalOHopeO

The answer is 7 I’m quite sure

14. The area of 10 square plots is 160 ares. Find the length in metres of the side of each plot (3mks)​

Answers

Answer:

Step-by-step explanation:

1 are = 100 m²

Assuming the ten squares are congruent, the area of each square is 160/10 = 16 are

16 are × 100 m²/are = 1600 m²

each side is √1600 = 40 m

The length of side of plot is 40 meters.

What is area?

The total space occupied by a flat (2-D) surface or shape of an object is known as area.

Draw a square on a piece of paper with a pencil. It has two dimensions. The term "area" refers to the area that the shape occupies on the paper.

Now picture your square as being comprised of smaller unit squares. The number of unit squares required to cover a 2-D shape's total surface area is used to calculate its area.

Given the area of 10 square plot is 160 are,

here 1 are = 100 m²

area of 10 square plot = 160 x 100 = 16,000 m²

area of 1 square plot = 16000/10 = 1600 m²

area of square is "a²"

where a is side of square

area = a² = 1600 m²

a = √1600

a = 40 m

Hence the length of side of each plot is 40 meters.

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Fewer and fewer customers have been coming into the restaurant, so Bill, the manager, decides to change the entire menu. After he does this, he finds out that people loved the food, but the service has been driving people away. This represents what kind of problem in the decision-making process? O a) Failure to develop enough options O b) Failure to correctly define the problem c) Failure to act on a decision O d) Failure to evaluate the decision

Answers

Answer:

failure to correctly define the problem

Step-by-step explanation:

He changes the menu without identify that the real problem was the service.

Which of the following are exterior angles? Check all that apply.

Answers

Answer:

<5

Step-by-step explanation:

exterior angles + the corresponding interior angle of the triangle = 180º or a straight angle

the only exterior angle shown in the diagram is <5, which corresponds to the interior <2

hope this helps!

Answer:

<5

Step-by-step explanation:

everything else is matched up perfectly so it has to be <5

Correct the formula
Please

Answers

Answer:

The addition should be divided by 4 and not 3 since there are 4 meals.

Step-by-step explanation:

What is the total cost of a $28 pair of jeans if the sales tax is 7.5%?

Answers

Answer:

30.10

Step-by-step explanation:

First find the amount of tax

28 * 7.5%

28 * .075

2.10

Add this to the price of the pants

28+2.10 =30.10

In 20P4 how many choices are
there for vice-president from a
state of four officers?
Note: The vice president is the second officer
to be elected.
Acellus

Answers

Answer:  B) 19

Explanation:

There are 20 choices for president, and 20-1 = 19 choices for vice president. You count down by 1 each time you fill a seat. So that means you'll have 19-1 = 18 choices for the third seat, and 18-1 = 17 choices for the fourth seat.

Find the probability. A calculator requires a keystroke assembly and a logic circuit. Assume that 75% of the keystroke assemblies and 94% of the logic circuits are satisfactory. Find the probability that a finished calculator will be satisfactory.

Answers

Answer:

0.705 = 70.5% probability that a finished calculator will be satisfactory.

Step-by-step explanation:

Probability of independent events:

If two events, A and B, are independent, the probability of both happening is the multiplication of the probabilities of each happening, that is:

[tex]P(A \cap B) = P(A)P(B)[/tex]

In this question:

Event A: Keystroke assembly are satisfactory.

Event B: Logic circuits are satisfactory.

75% of the keystroke assemblies and 94% of the logic circuits are satisfactory.

This means that [tex]P(A) = 0.75, P(B) = 0.94[/tex]

Find the probability that a finished calculator will be satisfactory.

Both satisfactory, and since they are independent:

[tex]P(A \cap B) = P(A)P(B) = 0.75*0.94 = 0.705[/tex]

0.705 = 70.5% probability that a finished calculator will be satisfactory.

round 12.5478 to the nearest hundredths

Answers

Answer:

12.04

Step-by-step explanation:

Find the number in the hundredth place  4  and look one place to the right for the rounding digit  1 . Round up if this number is greater than or equal to  5  and round down if it is less than  5 .

Write the phrase as an algebraic expression: 3 less than 4 times a number

Answers

Answer:

4x-3 is the expression to your question

Answer:

3[tex]\leq[/tex]4x

Step-by-step explanation:

help pls!!! Classify the following question: “President, vice president, and secretary are being chosen for the Environmental Club. In how many different ways can these three offices be filled from a list of ten members?”

Answers

the answer is: combation

A rectangle auditorium seats 1260 people. The number of seats in each row exceeds the number of rows by 12. Find the number of seats in each row

Answers

Answer:

Easy, all you ha

Step-by-step explanation:


f(x) = x - 1. Find the inverse of f(x).

Answers

Answer:

f^-1 (x) = x+1

Step-by-step explanation:

f(x) = x-1

y = x-1

Exchange x and y

x = y-1

Solve for y

Add 1 to each side

x+1 = y-1+1

x+1 = y

The inverse is x+1

f^-1 (x) = x+1

Copy center charges $0.08 a page for machine fed copies and $0.20 for hand fed copies.If Logan's bill for 80 copies of his movie script is $13, how many copies of each type were made?

Answers

Answer:

machine fed copies = 25, hand fed copies = 55

Step-by-step explanation:

let machine fed = x, hand fed = y

0.08x+0.2y = 13 (1)

x+y = 80

x= 80-y (2)

sub (2) into (1)

0.08(80-y)+0.2y=13

6.4-0.08y+0.2y=13

0.12y=6.6

y = 55

sub y=55 into eqn 2

x = 80-55 = 25

Expand (2+x)^-3







....

Answers

Answer:

1/(x^3 + 6x^2 + 12x + 8)

Step-by-step explanation:

The first thing we do is rationalize this expression. (2+x)^-3 is written as

1/(2+x)^3

Then from there we can foil out the denominator. It is easiest to foil (2+x)(2+x) first and then multiply that product by (2+x).

(2+x)(2+x) = 4 + 4x + x^2

(4+4x+x^2)(2+x) = 8+8x+2x^2+4x+4x^2+x^3.

Then we combine like terms and put them in order to get:

x^3 + 6x^2 + 12x + 8

And of course we can't forget that this was raised to the negative third power, so our answer is 1/(x^3 + 6x^2 + 12x + 8)

Answer:

Hello,

Step-by-step explanation:

[tex](a+x)^n=a^n+\left(\begin{array}{c}n\\ 1\end{array}\right)*a^{n-1}*x+\left(\begin{array}{c}n\\ 2\end{array}\right)*a^{n-2}*x^2+\left(\begin{array}{c}n\\ 3\end{array}\right)*a^{n-3}*x^3+\left(\begin{array}{c}n\\ 4\end{array}\right)*a^{n-4}*x^4+...+\left(\begin{array}{c}n\\ n\end{array}\right)*a^{n-n}*x^n[/tex]

[tex]with \\\\\left(\begin{array}{c}n\\ 1\end{array}\right)=n\\\\\left(\begin{array}{c}n\\ 2\end{array}\right)=\dfrac{n(n-1)}{2!} \\\\\left(\begin{array}{c}n\\3 \end{array}\right)=\dfrac{n(n-1)(n-2)}{3!} \\\\...\\[/tex]

[tex]\dfrac{1}{(2+x)^3} =\dfrac{1}{8} +3*\dfrac{x}{4}+3\dfrac{x^2}{2}+x^3\\\\[/tex]

What sum of money, invested at 9%
interest per year, is needed to provide an
income of $45 per year?

Answers

Answer:

$500

Step-by-step explanation:

Intrest = P. A * Intrest Rate * Time

Time = 1 year, Intrest Rate = 9%, P. A. is what we need to find, Intrest is 45

45=x*9/100*1, x=500

Answer:

500

Step-by-step explanation:

I = PRT  where I is the interest, P is the amount invested, R is the rate and T is the time

We want 1 year at 9% to get 45 dollars in interest

45 = P ( .09) (1)

45 = .09P

Divide each side by .09

45/ .09 = P

500 =P

How many solutions on the interval {0, 2020} sin 2x + 1 + sin x + cos x have?

Answers

Answer:

0

Step-by-step explanation:

Can someone check my answers if they are correct or incorrect? If it is incorrect, please let me know why it is incorrect please.

Answers

This answer is incorrect, try again

Can you please help me

Answers

Answer:

Step-by-step explanation:

⅝ - 5/9 = 5/72

5/72 I think it is :D

Instructions are in the picture

Answers

Answer:

123123 3213123 12312 dasdsd aw dasd sda asdasd

Step-by-step explanation:

Choose the correct answer.

The History Activities were about​ ___ and​ ___. They were both from​ ___. One of them had a​ ___ named after him. The other had a​ ___ named after him. The work they did together on a problem they got from a​ ___ laid the foundation for probability theory.

A. ​Pascal, Decartes,​ England, graph,​ book, relative
B. ​Luniz, Kolmogrov,​ Germany, church,​ square, teacher
C. ​Fermat, Luniz,​ England, law,​ diagram, priest
D. ​Pascal, Fermat,​ France, triangle,​ theorem, gambler

Answers

Answer:

I say Its letter d

Step-by-step explanation:

I hope this help

Algebra II Part 1
On your paper, graph these coordinates:
(-1, 1), (-5, 2)
Type the correct equation of the line.
Note: Do not use fractions in your answer.

Answers

Answer:

4y+x-3=0

Step-by-step explanation:

The equation is y=mx+b

1) Use the coordinates from the first point

(-1,1)

1= -m+b

2) Use the coordinates frm the second point

(-5,2) (y=mx+b, use x=-5, y=2)

2=-5m+b

You have the system of equations

1=-m+b (multiply by -1)  -1= m-b

2=-5m+b

Add the first equation (multiplied by -1) and the second one

-1+2= m-b-5m+b

1= -4m

m=-0.25

2=1.25+b

b=0.75

y=-0.25x+0.75

4y= -x+3

4y+x-3=0

FX) is defined by the equation f(x) = 4x2 - 2x +17. What effect will multiplying
f(x) by 0.5 have on the graph?
A. The graph will be stretched horizontally.
B. The graph will be compressed horizontally.
C. The graph will be stretched vertically.
D. The graph will be compressed vertically.

Answers

Step-by-step explanation:

the graph will be compressed vertically

Which of the following is a quadratic function

Answers

A quadratic a function has a form of,

[tex]f(x)=ax^2+bx+c,a\neq0[/tex]

The first function has a term [tex]x^3[/tex] which doesn't fit the profile of a quadratic function. The highest exponent on x inside a quadratic function can be 2, but here we have 3 so this is not a quadratic function, but rather a cubic function.

The second function fits the form of a quadratic function perfectly.

The third function is a bit tricky. While technically the third function could be considered quadratic if the leading term would be something like [tex]0x^2[/tex] and we did't even see it written out because multiplying with 0. But when we specified the form of a quadratic function, we strictly said that the number before [tex]x^2[/tex] aka [tex]a[/tex] cannot equal to zero. So the last function is not a quadratic function but rather a linear function.

Hope this helps :)

Step-by-step explanation:

f(x) = 4x² + x - 3

[tex]f(x) = 4x {}^{2} + 3 - 2[/tex]

r3t40 is correct

Instructions: Find the area of the trapezoid
and round to the nearest tenth.
10.2 mi.
7 mi.
4.2 mi.
Area:
mi?

Answers

Answer:

299.88 mi. !!!!!

you just multiple all of them together to get the area!!!

Can someone please help me
Researchers would like to assess the overall health of white pine trees in a state park. Which of the following
methods for choosing the trees to assess would be considered a convenience sample?
O A ranger hires employees to assess every tree in the park.
O The 100 trees closest to a ranger station are assessed for damage.
O Agrid map of the park is used, and 100 random points on the grid are chosen and used to select the trees to
assess
O Each tree in the state park is tagged with a number, and 100 random numbers that represent the trees are
selected and assessed for damage.

Answers

Answer:

The 100 trees closest to a ranger station are assessed for damage.

Step-by-step explanation:

Convenience samples are samples taken from only around the focal point.

Option B is correct, The 100 trees closest to a ranger station are assessed for damage.

What is Statistics?

Statistics is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data.

A convenience sample is a non-random method of sampling that involves selecting subjects that are easy to access or readily available.

Of the methods listed, the convenience sample is the one where the trees are selected based on their proximity to a ranger station:

The 100 trees closest to a ranger station are assessed for damage.

This method is a convenience sample because it does not involve random selection of trees.

Instead, the trees are chosen based on their proximity to a specific location.

This can introduce bias into the sample, as trees near the ranger station may not be representative of the overall health of white pine trees in the state park.

Hence, Option B is correct, The 100 trees closest to a ranger station are assessed for damage.

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Assume that two marbles are drawn without replacement from a box with 1 blue, 3 white, 2 green, and 2 red marbles. Find the probability that the first marble is white and the second marble is blue.

Answers

Answer:

3/56

Step-by-step explanation:

Probability is the ratio of the number of possible outcome to the number of total outcome.

Given that two marbles are drawn without replacement from a box with 1 blue, 3 white, 2 green, and 2 red marbles.

The total number of marbles in the box

= 1 + 3 + 2 + 2

= 8 marbles

The probability that the first marble is white and the second marble is blue

= 3/8 * 1/7

= 3/56

Other Questions
When comparing the results of using the direct, sequential, and reciprocal services methods of allocating support department costs to production departments, which of the following statements is true for a manufacturing company that has a total of $1,500,000 in support costs to allocate?a.The reciprocal services method allocates more than $1,500,000 to the production departments.b.The reciprocal services method can be viewed as a compromise on accuracy and difficulty in allocating the $1,500,000 because it considers some, though not all, inter-support-department services and is easier to compute than the direct method.c.The direct method yields the most accurate allocation of the $1,500,000.d.The sequential method can be viewed as a compromise on accuracy and difficulty in allocating the $1,500,000 because it considers some, though not all, inter-support-department services and is easier to compute than the reciprocal services method. change following questions into active voice (a)social media tears down communication and distance barriers Suppose that 17 inches of wire costs 68 cents,At the same rate, how much (in cents) will 39 inches of wire cost?cents? 7 x ..... = 364 whats the missing number ? Select the correct answer.Why might two elements possess similar chemical properties?OA. They belong to the same group of the periodic table.OB. They have the same physical state.OC. They have similar physical properties.OD. They belong to the same period of the periodic table.ResetNext2021 Edmentum. All rights reserved. Find the height of the room 15m long amd 10 m wide . The area of whose floor and ceiling together is equal to the area of 4 walls Paul is complimenting people. Choose the appropriate adjective indicated in parenthesis, make any necessary agreements and write the adjective in the correct blank. You will fill in only one blank in each sentence. Place an X in the blank that is left empty. explain about nutritious food 18. If the pH of a strong acid solution is known to be 3.25, what is the [H+)?(b) what is the pOH of this solution? Annie is opening a savings account which earns 5.2% interest compounded continuously how much will she need to deposit in the account so she has $2300 after seven years PLEASE HELP! I HAVE BEEN AT THIS FOR A LONG TIME!.For each investement, 25 000 is deposited in an account. How much is each payment?(a. 8% per annum, compounded annually, with annual payments starting in a year. write an Article for youe teacher for sports lesson Can anyone answer this easy question!. 1. Give me 7 facts about spain please someone Fastest answer will be declared the brainliest what is 2x2x2x3x3 please give me answer Find the length of BWA.132.59B.134.24C.21.26D.3.33 how do religion and school contribute to socialization Nombre de la siguiente estructura de compuesto orgnico I need help ASAP please! What kind of shape will you see if you cut a cross section parallel to the base of a cylinder