A tank originally contains 100 gallon of fresh water. Then water containing 0.5 Lb of salt per gallon is pourd into the tank at a rate of 2 gal/minute, and the mixture is allowed to leave at the same rate. After 10 minute the process is stopped, and fresh water is poured into the tank at a rate of 2 gal/min, with the mixture again leaving at the same rate. Find the amount of salt in the tank at end of an additional 10 minutes.

Answers

Answer 1

Let [tex]S(t)[/tex] denote the amount of salt (in lbs) in the tank at time [tex]t[/tex] min up to the 10th minute. The tank starts with 100 gal of fresh water, so [tex]S(0)=0[/tex].

Salt flows into the tank at a rate of

[tex]\left(0.5\dfrac{\rm lb}{\rm gal}\right) \left(2\dfrac{\rm gal}{\rm min}\right) = 1\dfrac{\rm lb}{\rm min}[/tex]

and flows out with rate

[tex]\left(\dfrac{S(t)\,\rm lb}{100\,\mathrm{gal} + \left(2\frac{\rm gal}{\rm min} - 2\frac{\rm gal}{\rm min}\right)t}\right) \left(2\dfrac{\rm gal}{\rm min}\right) = \dfrac{S(t)}{50} \dfrac{\rm lb}{\rm min}[/tex]

Then the net rate of change in the salt content of the mixture is governed by the linear differential equation

[tex]\dfrac{dS}{dt} = 1 - \dfrac S{50}[/tex]

Solving with an integrating factor, we have

[tex]\dfrac{dS}{dt} + \dfrac S{50} = 1[/tex]

[tex]\dfrac{dS}{dt} e^{t/50}+ \dfrac1{50}Se^{t/50} = e^{t/50}[/tex]

[tex]\dfrac{d}{dt} \left(S e^{t/50}\right) = e^{t/50}[/tex]

By the fundamental theorem of calculus, integrating both sides yields

[tex]\displaystyle S e^{t/50} = Se^{t/50}\bigg|_{t=0} + \int_0^t e^{u/50}\, du[/tex]

[tex]S e^{t/50} = S(0) + 50(e^{t/50} - 1)[/tex]

[tex]S = 50 - 50e^{-t/50}[/tex]

After 10 min, the tank contains

[tex]S(10) = 50 - 50e^{-10/50} = 50 \dfrac{e^{1/5}-1}{e^{1/5}} \approx 9.063 \,\rm lb[/tex]

of salt.

Now let [tex]\hat S(t)[/tex] denote the amount of salt in the tank at time [tex]t[/tex] min after the first 10 minutes have elapsed, with initial value [tex]\hat S(0)=S(10)[/tex].

Fresh water is poured into the tank, so there is no salt inflow. The salt that remains in the tank flows out at a rate of

[tex]\left(\dfrac{\hat S(t)\,\rm lb}{100\,\mathrm{gal}+\left(2\frac{\rm gal}{\rm min}-2\frac{\rm gal}{\rm min}\right)t}\right) \left(2\dfrac{\rm gal}{\rm min}\right) = \dfrac{\hat S(t)}{50} \dfrac{\rm lb}{\rm min}[/tex]

so that [tex]\hat S[/tex] is given by the differential equation

[tex]\dfrac{d\hat S}{dt} = -\dfrac{\hat S}{50}[/tex]

We solve this equation in exactly the same way.

[tex]\dfrac{d\hat S}{dt} + \dfrac{\hat S}{50} = 0[/tex]

[tex]\dfrac{d\hat S}{dt} e^{t/50} + \dfrac1{50}\hat S e^{t/50} = 0[/tex]

[tex]\dfrac{d}{dt} \left(\hat S e^{t/50}\right) = 0[/tex]

[tex]\hat S e^{t/50} = \hat S(0)[/tex]

[tex]\hat S = 50 \dfrac{e^{1/5}-1}{e^{1/5}} e^{-t/50}[/tex]

After another 10 min, the tank has

[tex]\hat S(10) = 50 \dfrac{e^{1/5}-1}{e^{1/5}} e^{-1/5} = 50 \dfrac{e^{1/5}-1}{e^{2/5}} \approx \boxed{7.421}[/tex]

lb of salt.


Related Questions

Plz help! Answer at least one of these questions and i will give you brainly! It’s ok if you don’t know them all!

Answers

for number 3 it is 56 pints! i’ll do the other ones in a second
3: 7gallons = 56 pints

As a car moves along a section of the roadway in a mountain pass, it passes through a horizontal run of 950 feet and through a vertical rise of 35 feet. To the nearest foot, how far does the car move along the roadway?

Answers

Answer:

I believe it will be 55.9 or 56 along the roadway

Step-by-step explanation:

Hope this Helped

HELP AGAIN I NEED IT BADLY

Answers

Answer:

A. 5b - w + 8

Step-by-step explanation:

3w + 6 - 4w + 3b + 2 + 2b

= 3w - 4w + 3b + 2b + 6 + 2

= -w + 5b + 8

= 5b - w + 8

=> A. 5b - w + 8

Solve the following for c: 10c + 12 = - 48

Answers

Answer:

c = -6

Step-by-step explanation:

10c + 12 = -48

subtract 12 from both sides

10c = -60

divide by 10 on both sides

c = -6

Answer:

C = -6

Step-by-step explanation:

10c + 12 = - 48

      -12     -12

10c = -60

/10     /10

c = -6

Your friend arrives and placed pieces appropriately on the board. What percent of the checker board squares have pieces?

URGENT I WILL GIVE BRAINLIEST TO CORRECT ANSWER

Answers

Answer:

25% of the board is covered with checker pieces.

Step-by-step explanation:

Answer:

If it's just for the pieces shown, it's just 0.125 or 12.5%, but if it's saying to include both sides (even though the picture doesn't represent this), it's just 0.25 or 25%

Step-by-step explanation:

8/64 or 16/64

A new medical test has been designed to detect the presence of the mysterious Brainlesserian disease. Among those who have the disease, the probability that the disease will be detected by the new test is 0.7. However, the probability that the test will erroneously indicate the presence of the disease in those who do not actually have it is 0.08. It is estimated that 18 % of the population who take this test have the disease.
You may want to construct a table as in your course materials. Use a population of 10,000 people.If the test administered to an individual is positive, what is the probability that the person actually has the disease?Express your answer rounded correctly to three decimal places.

Answers

Solution :

It is given that :

P (positive | Has disease) = 0.7

P (positive | No disease) = 0.08

P (has disease) = 0.18

P (No disease) = 1 - 0.18

                        = 0.82

Now if test administered to the individual is positive, the probability that the person actually have the disease is

P (Has disease | positive)  [tex]$=\frac{P(\text{positive}| \text{has positive}) \times P(\text{Has disease})}{P(\text{positive})}$[/tex]  ......(1)

The P(positive) is,

[tex]$P(\text{positive}) = P(\text{positive} \cap \text{Has disease})+P(\text{positive} \cap \text{No disease})$[/tex]

                = P(positive | has disease) x P(Has disease) + P(positive | no disease) x P(No disease)

                 = 0.7 (0.19) + 0.04 (0.81)

                = 0.1654

Now substituting the values in the equation (1), we get

P (Has disease | positive)  [tex]$=\frac{P(\text{positive}| \text{has positive}) \times P(\text{Has disease})}{P(\text{positive})}$[/tex]  

                                           [tex]$=\frac{0.7(0.19)}{0.1654}$[/tex]

                                          = 0.8041  

You're selling tickets to a school play priced at $5 for students, $10 for parents, and $20 for general admission. The total sales are $2,500, you sell twice as many parent tickets as student tickets, and you selll 10 more students tickets than general admission. How many of each ticket did you sell?

A:60 student, 120 parent, and 50 general admission
B:40 student, 80 parent, and 30 general admission
C:80 student, 160 parent, and 70 general admission
D:90 student, 45 parent, and 80 general admission

Answers

Answer:

A

Step-by-step explanation:

y+2=1/5(x+1)
graph?

Answers

Or in order pair form ( 0 , 9 )

Answer:

x=5Y+9, Plot on graph 1/5x-9/5

Step-by-step explanation:

The x intercept is (9,0)

The Y intercept is (0,-9/5)

Substitute w = 1 and w = 3 to determine if the two expressions are equivalent.

Answers

Answer:

mineeeeeeeeeeee

Step-by-step explanation:

REWRITE EACH PROBLEM AS A MULTIPLICATION QUESTION!

Hunter spent 2/3 of his money on a video game before spending half of his remaining money on lunch. If his lunch costs 10 dollars, how much money did he have at first?​

Answers

Answer:

$60, because if $10 is half, then before lunch Hunter had $20.

If Hunter used 2/3 of his money to buy that video game, and remained with $20 that means that 1/3 of the original amount of money he had was $20.

$20 * 3 = $60. Hunter began with $60.

Step-by-step explanation:

hope this helped you! :)

please help me thank you

Answers

Answer:

y= - 1/6x-2

I hope it helped

Let the amount of money Tabitha started with be represented by x.
Tabitha then earned $52, spent $40,earned $28, and spent $58.How
much money, in terms of x, does Tabitha have now?

Answers

If Tabitha started with $50, then she would have $38 left.

Step-by-step explanation:

50 + 52 = 102.

102 - 40 = 62.

62 + 28 = 90.

90 - 58 = 38.

Answer:

38

Step-by-step explanation:

hi

AD is tangent to circle B at point C. What is the measure of angle BCA.

Answers

Answer:

90°

Step-by-step explanation:

Actually the question should be AC is tangent to circle B at point C. What is the measure of angle BCA.

AC is tangent and BC is radius.

Radius is perpendicular to the tangent.

Therefore,

measure of angle BCA = 90°

Consider the linear function y = 5x + 12 and the linear function represented by the table of values below.

Answers

Answer:

(a) and (f)

Step-by-step explanation:

Given

[tex]y = 5x + 12[/tex]

See attachment for table and options

First, we calculate the slope of the table

[tex]m = \frac{y_2 - y_1}{x_2 - x_1}[/tex]

Using:

[tex](x_1,y_1) = (2,29)[/tex]

[tex](x_1,y_1) = (4,53)\\[/tex]

So, we have:

[tex]m = \frac{53- 29}{4 - 2}[/tex]

[tex]m = \frac{24}{2}[/tex]

[tex]m = 12[/tex]

The equation is then calculated using:

[tex]y = m(x -x_1) + y_1[/tex]

This gives:

[tex]y = 12*(x -2) + 29[/tex]

[tex]y = 12x -24 + 29[/tex]

[tex]y = 12x+5[/tex]

So, we have:

[tex]y = 5x + 12[/tex] --- The given equation

and

[tex]y = 12x+5[/tex] --- The equation of the table

An equation is represented as:

[tex]y = mx + b[/tex]

Where:

m = slope or rate of change

b = y intercept

So, for the given equation: [tex]y = 5x + 12[/tex]

Rate of change = 5

y intercept = 12

For the table: [tex]y = 12x+5[/tex]

Rate of change = 12

y intercept = 5

In conclusion:

(a) [tex]y = 12x+5[/tex] has the greater rate of change:

and

(f) [tex]y = 5x + 12[/tex] has the greater y intercept

graph of function f(x)=1/x+7-14

Answers

Find the asymptotes.
Vertical Asymptotes: x=0
Horizontal Asymptotes: y= -7
No Oblique Asymptotes

Length of time for a shower and the amount of water used

A. Positive association

B. Negative association

C. No association

Answers

I think it’s negative association, the more time you use the shower the more water you have used

Allentown, Bakersfield, and Cowville are not in a line. If it is 57 miles in aline from Allentown to Bakersfield and 35 miles from Bakersfield to Cowville , how far is it from Allentown to Cowville?

Answers

Answer:

27

Step-by-step explanation:

322415154551

Answer:

92

Step-by-step explanation:

Just simply add 57 to 35.

57+35=92

Andre bought a new bag of cat food. The next day, he opened it to feed his cat. The graph shows how many ounces were left in the bag on the days after it was bought.

How much did the bag weigh before it was opened?

Answers

Answer:
There were 16 ounces of Cat Food after 24 days.
Step-by-step explanation:
From the graph attached,
For an ordered pair (x, y) lying on the graph,
x-coordinate represents the number of days since bag was bought and y- coordinate represents the ounces of cat food required.
Now the value x = 24 on x-axis shows the number of days since the bag was bought.
For x = 24, ounces of cat food in the bag ( y ) = 16 ounce
Therefore, 16 ounces of Cat Food were in the bag after 24 days since it was bought.

Answer:

There were 16 ounces of Cat Food after 24 days.

If Jimmy boy here has 35 ropes and he washes 56 paper, how much wetlands will Johnny Boy own left.

Answers

Answer:

All of what he had

Step-by-step explanation:

Answer: jimmy will have it all

Step-by-step explanation:

a scale drawing of a rectangular park is 5 inches wide and 7 inches long. The actual park is 10,080 inches long What is the width of the actual park, in inches

Answers

Shorter Answer:

7 inches → 280 yards

1 inch → 280 ÷ 7 = 40 yards

5 inches → 40 x 5 = 200 yards

Area = 280 x 200 = 56 000 yards

Answer: 56 000 yards

LongerAnswer (going more into depth):

Area of the actual park is 56000 square yards.

Step-by-step explanation:

A scale drawing of a rectangular park has dimensions as 5 inches width and 7 inches length.

Actual length of the park has been given as 280 yards.

So scale factor used in the drawing is 7 inches = 280 yards

Or 1 inch = 40 yards

Since width of the rectangular park is = 5 inch  

So actual width of the park will be = 5×40 = 200 yards

Now we can calculate the area of the park.

Actual area of the park = Length × Width

= 280×200

= 56000 yards²

Therefore, area of the actual park is 56000 square yards.

If my radius is 10 feet, what is my diameter?

Answers

Answer:

Your diameter would be 20.

Step-by-step explanation:

1. Two radius added together is the diameter (if you're talking about a circle.)

2. You add 10+10 because as you said your radius is 10.

3. It would be 20.

Hope this helped!

7. What is the DEGREE of the following binomial:
3x-2

Answers

I believe the answer is 1

1000-(864%2+336%3+648%2)=

Answers

Answer:

959.72

Step-by-step explanation:

you have to simplify

Step-by-step explanation:

=1000-864%2-336%3-648%2

=1000-17.28-10.08-12.96

=-11123.36

The buyer of a lot pays 50,000 and 10,000 every month for 10 yearts and is worth 8% compounded monthly

Answers

Answer:

d

Step-by-step explanation:

of course it is Charlie as he just walked 11.8 miles

The length of a rectangle is 4 inches longer than it is wide. If the perimeter is 52 inches, what are the
dimensions of the rectangle?

Answers

Answer:

L = 15

W = 11

Step-by-step explanation:

P = 2L + 2W

2L + 2W = 52                         Divide each term by 2

2L/2 + 2W/2 = 52/2

L + W = 26                              Substitute the value for L

W + 4 + W = 26                      

2W + 4 = 26

2W = 26 - 4                            Subtract 4 from both sides

2W = 22                                  Divide by 2

W = 22 /2

W = 11

L = W + 4

L = 11 + 4

L = 15

DASAROLLA:

a) (x+3) (x+5)=

b) (x+4) (x-5)=​

Answers

Answer:

a)[tex]x^{2}[/tex]+8x+15

b)[tex]x^{2}[/tex]-x-20

Step-by-step explanation:

a) (x+3)(x+5)

a)[tex]x^{2}[/tex]+5x+3x+15

a)[tex]x^{2}[/tex]+8x+15

b) (x+4)(x-5)

b) [tex]x^{2}[/tex]-5x+4x-20

b)[tex]x^{2}[/tex]-x-20

solve 3e = -27 show work
this one i dont understand how to do​

Answers

Answer:

-9

Step-by-step explanation:

This would be -27/3 = -9

Decide if the following is a true or false statement - explain how you know

(- 1/2) - (4.25) is positive

Answers

Answer:

False

Step-by-step explanation:

The equation equals -1/2 - 4.25 which is -4.75, which is negative.

Hope that helps!

A washer and a dryer cost $450 combined. The cost of the washer is two times the cost of the dryer. What is the cost of the dryer?

Answers

Answer:

$150

Step-by-step explanation:

so you can divvy this up into 3 parts

$150 each

now put 2 parts into one, and one into the other. The cost of the washer is $150

cost of the dryer is$ 300

Which value of x makes the two matrices inverses of each other?
5
2
1
-2
2
1
5
-2
-1
2

Answers

Answer:

A: -2

Step-by-step explanation:

TOOK THE TEST

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