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1 year ago

10

A city has a population of 350000 the population has decreased by 30% in the past ten years what was the population Of the city

ten years ago. Show solving steps

1 answer:

FromTheMoon [43]1 year ago

4 0

Answer:

30% x 350000 + 105000

Step-by-step explanation:

30

100

(350000)

=(

30

100

)(

350000

1

)

=(

3

10

)(

350000

1

)

=

(3)(350000)

(10)(1)

=

1050000

10

=105000

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Suppose that a large mixing tank initially holds 500 gallons of water in which 50 pounds of salt have been dissolved. Another br

aliya0001 [1]

Answer:

$A=1500-1450e^{-\dfrac{t}{250}}$

Step-by-step explanation:

The large mixing tank initially holds 500 gallons of water in which 50 pounds of salt have been dissolved.

Volume = 500 gallons

Initial Amount of Salt, A(0)=50 pounds

Brine solution with concentration of 2 lb/gal is pumped into the tank at a rate of 3 gal/min

$R_{in}$ =(concentration of salt in inflow)(input rate of brine)

$=(2\frac{lbs}{gal})( 3\frac{gal}{min})\\R_{in}=6\frac{lbs}{min}$

When the solution is well stirred, it is then pumped out at a slower rate of 2 gal/min.

Concentration c(t) of the salt in the tank at time t

Concentration, $C(t)=\dfrac{Amount}{Volume}=\dfrac{A(t)}{500}$

$R_{out}$ =(concentration of salt in outflow)(output rate of brine)

$=(\frac{A(t)}{500})( 2\frac{gal}{min})\\R_{out}=\dfrac{A}{250}$

Now, the rate of change of the amount of salt in the tank

$\dfrac{dA}{dt}=R_{in}-R_{out}$

$\dfrac{dA}{dt}=6-\dfrac{A}{250}$

We solve the resulting differential equation by separation of variables.

$\dfrac{dA}{dt}+\dfrac{A}{250}=6\\$The integrating factor: e^{\int \frac{1}{250}dt} =e^{\frac{t}{250}}\\$Multiplying by the integrating factor all through\\\dfrac{dA}{dt}e^{\frac{t}{250}}+\dfrac{A}{250}e^{\frac{t}{250}}=6e^{\frac{t}{250}}\\(Ae^{\frac{t}{250}})'=6e^{\frac{t}{250}}$

Taking the integral of both sides

$\int(Ae^{\frac{t}{250}})'=\int 6e^{\frac{t}{250}} dt\\Ae^{\frac{t}{250}}=6*250e^{\frac{t}{250}}+C, $(C a constant of integration)\\Ae^{\frac{t}{250}}=1500e^{\frac{t}{250}}+C\\$Divide all through by e^{\frac{t}{250}}\\A(t)=1500+Ce^{-\frac{t}{250}}$

Recall that when t=0, A(t)=50 (our initial condition)

$50=1500+Ce^{-\frac{0}{250}}50=1500+Ce^{0}\\C=-1450\\$Therefore the amount of salt in the tank at any time t is:\\A=1500-1450e^{-\dfrac{t}{250}}$

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3 years ago

8.5/1.2=t/6.5 how to solve

ivanzaharov [21]

The answer for t is 46.0416

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3 years ago

John's fishing boat caught 2735 lbs of fish. They put them into boxes of 92 lbs each. About how many boxes did they need?

umka21 [38]

2735/92= 29.73 about 30 boxes

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3 years ago

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2) Consider the quadratic sequence 72, 100, 120, 132

slava [35]

Answer:

Tn = -4n²+40n+36

Step-by-step explanation:

A general quadratic sequence, Tn = an²+bn+c, where n is the term of the sequence.

So, when n = 1, Tn = 72, which means T1 = a+b+c=72.

when n = 2, Tn = 100, which means T2= 4a+2b+c = 100

when n = 3, Tn = 132, which means T3 = 9a+3b+c = 132.

Now, use a calcaulatot to solve the 3 variable simultaneous equation. According to my calculator, a = -4, b = 40, c = 36.

Hence, you a, b, and c in the Tn equation given above.

Therefore, <em>Tn = -4n²+40n+36</em>

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3 years ago

Solve for x in the diagram below.

larisa [96]

Answer:

x = 20

Step-by-step explanation:

The three angles form a straight line so they add to 180 degrees

x+ 100 +3x = 180

Combine like terms

100+4x= 180

Subtract 100 from each side

100+4x-100= 180-100

4x= 80

Divide each side by 4

4x/4 = 80/4

x = 20

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