Ask question

Ask question

All categories

2 years ago

10

By the end of the day, a 45 ft x 25 ft x 8 ft office has a carbon dioxide air level of 1,100 ppm. Determine the time in hours ne

cessary to reduce this concentration to ambient levels (approximately 325 ppm) assuming 20% of the return is "fresh" makeup air and there are two air changes per hour.

1 answer:

Julli [10]2 years ago

6 0

The total hours that are necessary to reduce carbon dioxide level to at least 325 ppm are 4 hours.

<h3>How does carbon dioxide concentration change over time?</h3>

First hour:

1,100 - 20 %
1,100 - 220 = 880

880 - 20%
880 - 176 = 704

Second hour:

704 - 20%
704 - 140.8 =663.2

663.2 - 20%
663.2 - 132.64 = 530.56

Third hour:

530.56 - 20%
530.56 - 106.112 = 424.44

424.44 - 20%
424.44 - 84.88 = 339.55

Fourth hour:

339.55 - 20%
339.55 - 67.91 = 271.64

Learn more about carbon dioxide in: brainly.com/question/3049557

#SPJ1

You might be interested in

La probabilidad de que un nuevo producto tenga éxito es de 0.85. Si se eligen 10 personas al azar y se les pregunta si compraría

liq [111]

Answer:

La probabilidad pedida es $0.820196$

Explanation:

Sabemos que la probabilidad de que un nuevo producto tenga éxito es de 0.85. Sabemos también que se eligen 10 personas al azar y se les pregunta si comprarían el nuevo producto. Para responder a la pregunta, primero definiremos la siguiente variable aleatoria :

$X:$ '' Número de personas que adquirirán el nuevo producto de 10 personas a las que se les preguntó ''

Ahora bien, si suponemos que la probabilidad de que el nuevo producto tenga éxito se mantiene constante $(p=0.85)$ y además suponemos que hay independencia entre cada una de las personas al azar a las que se les preguntó ⇒ Podemos modelar a $X$ como una variable aleatoria Binomial. Esto se escribe :

$X$ ~ $Bi(n,p)$ en donde $''n''$ es el número de personas entrevistadas y $''p''$ es la probabilidad de éxito (una persona adquiriendo el producto) en cada caso.

Utilizando los datos ⇒ $X$ ~ $Bi(10,0.85)$

La función de probabilidad de la variable aleatoria binomial es :

$p_{X}(x)=P(X=x)=\left(\begin{array}{c}n&x\end{array}\right)p^{x}(1-p)^{n-x}$ con $x=0,1,2,...,n$

Si reemplazamos los datos de la pregunta en la función de probabilidad obtenemos :

$P(X=x)=\left(\begin{array}{c}10&x\end{array}\right)(0.85)^{x}(0.15)^{10-x}$ con $x=0,1,2,...,10$

Nos piden la probabilidad de que por lo menos 8 personas adquieran el nuevo producto, esto es :

$P(X\geq 8)=P(X=8)+P(X=9)+P(X=10)$

Calculando $P(X=8), P(X=9)$ y $P(X=10)$ por separado y sumando, obtenemos que $P(X\geq 8)=0.820196$

7 0

3 years ago

Bending is defined as? A. the application of a load tending to distort a member in one direction. B. the application of opposing

amm1812

Hi how are you today

4 0

3 years ago

What is the worlds fastest car

Aneli [31]

Answer:

Thrust SSC

Explanation:

You can look it up

3 0

3 years ago

Read 2 more answers

In tropical climates, the water near the surface of the ocean remains warm throughout the year as a result of solar energy absor

mote1985 [20]

Answer:

7.07%

Explanation:

Thermal efficiency can be by definition seen as the ratio of the heat utilized by a heat engine to the total heat units in the fuel consumed.

We will determine the thermal efficiency of the given problem at the attached file.

7 0

3 years ago

Given the vector current density J = 10rho2zarho − 4rho cos2 φ aφ mA/m2:

Xelga [282]

Answer:

(a) Current density at P is $J(P)=180.\textbf{a}_{\rho}-9.\textbf{a}_{\phi} \ (mA/m^2)\\$ .

(b) Total current I is 3.257 A

Explanation:

Because question includes symbols and formulas it can be misunderstood. In the question current density is given as below;

$J=10\rho^2z.\textbf{a}_{\rho}-4\rho(\cos\phi)^2\textbf{a}_{\phi}\\$

where $\textbf{a}_{\rho}$ and $\textbf{a}_{\phi}$ unit vectors.

(a) In order to find the current density at a specific point <em>(P)</em>, we can simply replace the coordinates in the current density equation. Therefore

$J(P(\rho=3, \phi=30^o,z=2))=10.3^2.2.\textbf{a}_{\rho}-4.3.(\cos(30^o)^2).\textbf{a}_{\phi}\\\\J(P)=180.\textbf{a}_{\rho}-9.\textbf{a}_{\phi} \ (mA/m^2)\\$

(b) Total current flowing outward can be calculated by using the relation,

$I=\int {\textbf{J} \, \textbf{ds}$

where integral is calculated through the circular band given in the question. We can write the integral as below,

$I=\int\{(10\rho^2z.\textbf{a}_{\rho}-4\rho(\cos\phi)^2\textbf{a}_{\phi}).(\rho.d\phi.dz.\textbf{a}_{\rho}})\}\\\\I=\int\{(10\rho^2z).(\rho.d\phi.dz)\}\\\\\\$

due to unit vector multiplication. Then,

$I=10\int\(\rho^3z.dz.d\phi$

where $\rho=3,\ 0$ . Therefore

$I=10.3^3\int_2^{2.8}\(zdz.\int_0^{2\pi}d\phi\\I=270(\frac{2.8^2}{2}-\frac{2^2}{2} )(2\pi-0)=3257.2\ mA\\I=3.257\ A$

4 0

3 years ago