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3 years ago

One kilometer is approximately 31/50 mile. what decimal represents this length?

Mathematics

1 answer:

ollegr [7]3 years ago

7 0

0.62

31X2=62
50X2=100
62 divided by 100 is 0.62

Hope that helps! :)

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A 200-gal tank contains 100 gal of pure water. At time t = 0, a salt-water solution containing 0.5 lb/gal of salt enters the tan

Artyom0805 [142]

Answer:

1) $\frac{dy}{dt}=2.5-\frac{3y}{2t+100}$

2) $y(t)=(50+t)- \frac{12500\sqrt{2} }{(50+t)^{\frac{3}{2} }}$

3) 98.23lbs

4) The salt concentration will increase without bound.

Step-by-step explanation:

1) Let $y$ represent the amount of salt in the tank at time t, where t is given in minutes.

Recall that: $\frac{dy}{dt}=rate\:in-rate\:out$

The amount coming in is $0.5\frac{lb}{gal}\times 5\frac{gal}{min}=2.5\frac{lb}{min}$

The rate going out depends on the concentration of salt in the tank at time t.

If there is $y(t)$ pounds of salt and there are $100+2t$ gallons at time t, then the concentration is: $\frac{y(t)}{2t+100}$

The rate of liquid leaving is is 3gal\min, so rate out is $=\frac{3y(t)}{2t+100}$

The required differential equation becomes:

$\frac{dy}{dt}=2.5-\frac{3y}{2t+100}$

2) We rewrite to obtain:

$\frac{dy}{dt}+\frac{3}{2t+100}y=2.5$

We multiply through by the integrating factor: $e^{\int \frac{3}{2t+100}dt }=e^{\frac{3}{2} \int \frac{1}{t+50}dt }=(50+t)^{\frac{3}{2} }$

to get:

$(50+t)^{\frac{3}{2} }\frac{dy}{dt}+(50+t)^{\frac{3}{2} }\cdot \frac{3}{2t+100}y=2.5(50+t)^{\frac{3}{2} }$

This gives us:

$((50+t)^{\frac{3}{2} }y)'=2.5(50+t)^{\frac{3}{2} }$

We integrate both sides with respect to t to get:

$(50+t)^{\frac{3}{2} }y=(50+t)^{\frac{5}{2} }+ C$

Multiply through by: $(50+t)^{-\frac{3}{2}}$ to get:

$y=(50+t)^{\frac{5}{2} }(50+t)^{-\frac{3}{2} }+ C(50+t)^{-\frac{3}{2} }$

$y(t)=(50+t)+ \frac{C}{(50+t)^{\frac{3}{2} }}$

We apply the initial condition: $y(0)=0$

$0=(50+0)+ \frac{C}{(50+0)^{\frac{3}{2} }}$

$C=-12500\sqrt{2}$

The amount of salt in the tank at time t is:

$y(t)=(50+t)- \frac{12500\sqrt{2} }{(50+t)^{\frac{3}{2} }}$

3) The tank will be full after 50 mins.

We put t=50 to find how pounds of salt it will contain:

$y(50)=(50+50)- \frac{12500\sqrt{2} }{(50+50)^{\frac{3}{2} }}$

$y(50)=98.23$

There will be 98.23 pounds of salt.

4) The limiting concentration of salt is given by:

$\lim_{t \to \infty}y(t)={ \lim_{t \to \infty} ( (50+t)- \frac{12500\sqrt{2} }{(50+t)^{\frac{3}{2} }})$

As $t\to \infty$ , $50+t\to \infty$ and $\frac{12500\sqrt{2} }{(50+t)^{\frac{3}{2} }}\to 0$

This implies that:

$\lim_{t \to \infty}y(t)=\infty- 0=\infty$

If the tank had infinity capacity, there will be absolutely high(infinite) concentration of salt.

The salt concentration will increase without bound.

6 0

2 years ago

Jessica buys a lamp that costs $35 and a table that costs $75.00. If the tax rate is 10%, what will be the total cost of the lam

shepuryov [24]

Hello there!

75 + 35 = 110

110 x 10% = 0.1

110 x 0.1 = 11 ( the 11 is your tax )

75 + 35 = 110

110 + 11 = 121

$121

Hope this helped!

3 0

3 years ago

Pqrs is a rhombus find the value of x and y

Dima020 [189]

I can’t seen the question so it is hard to answer

7 0

2 years ago

Read 2 more answers

mark's soup recipe makes 6 servings and uses 4 carrots and 2 potatoes. How many carrots and potatoes does he need for 15 serving

VLD [36.1K]

Let’s see, for 6 servings he needed 4 carrots, meaning every carrot was equal to 1.5 servings. 15/1.5 is 10, 10 carrots for 15 servings.

7 0

2 years ago

Find z if X=27, μ=20, and α=3.4. Round to the nearest hundredth if necessary.

Scrat [10]

Answer:

A. $Z=2.06$

Step-by-step explanation:

We want to find the Z-score of $X=27$ if the population mean is $\mu=20$ ,and the population standard deviation is $\sigma=3.4$ .

We use the formula:

$Z=\frac{X-\mu}{\sigma}$

We substitute the values to obtain:

$Z=\frac{27-20}{3.4}$

$Z=\frac{7}{3.4}$

$Z=2.06$

The correct answer is A.

7 0

3 years ago