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AleksAgata [21]

3 years ago

15

A biologist determined that the quantity of bacteria in a petri dish decreases by half every day of the study. If there were 8 g

rams of bacteria at the beginning of the study, predict how many grams will be left after 3.5 days. Round to the nearest hundredth

1 answer:

Anna [14]3 years ago

3 0

The sender is .75 grams

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Eventually the coat sales will be negative, which is not possible.

Eventually the temperature will increase or decrease to impossible values.

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Step-by-step explanation:

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3 years ago

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The sum of two numbers is 27. One number is 2 times as large as the other. What are the numbers?

mafiozo [28]

X+y=27
x=2y

2y+y=27
y=9

x=27-y
x=27-9=18

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3 years ago

CAN YOU HELP ME PLEASEEEE ITS GEOMETRY!!! THANK YOUUU

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Answer:

117

Step-by-step explanation:

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3 years ago

Problem 10: A tank initially contains a solution of 10 pounds of salt in 60 gallons of water. Water with 1/2 pound of salt per g

AysviL [449]

Answer:

The quantity of salt at time t is $m_{salt} = (60)\cdot (30 - 29.833\cdot e^{-\frac{t}{10} })$ , where t is measured in minutes.

Step-by-step explanation:

The law of mass conservation for control volume indicates that:

$\dot m_{in} - \dot m_{out} = \left(\frac{dm}{dt} \right)_{CV}$

Where mass flow is the product of salt concentration and water volume flow.

The model of the tank according to the statement is:

$(0.5\,\frac{pd}{gal} )\cdot \left(6\,\frac{gal}{min} \right) - c\cdot \left(6\,\frac{gal}{min} \right) = V\cdot \frac{dc}{dt}$

Where:

$c$ - The salt concentration in the tank, as well at the exit of the tank, measured in $\frac{pd}{gal}$ .

$\frac{dc}{dt}$ - Concentration rate of change in the tank, measured in $\frac{pd}{min}$ .

$V$ - Volume of the tank, measured in gallons.

The following first-order linear non-homogeneous differential equation is found:

$V \cdot \frac{dc}{dt} + 6\cdot c = 3$

$60\cdot \frac{dc}{dt} + 6\cdot c = 3$

$\frac{dc}{dt} + \frac{1}{10}\cdot c = 3$

This equation is solved as follows:

$e^{\frac{t}{10} }\cdot \left(\frac{dc}{dt} +\frac{1}{10} \cdot c \right) = 3 \cdot e^{\frac{t}{10} }$

$\frac{d}{dt}\left(e^{\frac{t}{10}}\cdot c\right) = 3\cdot e^{\frac{t}{10} }$

$e^{\frac{t}{10} }\cdot c = 3 \cdot \int {e^{\frac{t}{10} }} \, dt$

$e^{\frac{t}{10} }\cdot c = 30\cdot e^{\frac{t}{10} } + C$

$c = 30 + C\cdot e^{-\frac{t}{10} }$

The initial concentration in the tank is:

$c_{o} = \frac{10\,pd}{60\,gal}$

$c_{o} = 0.167\,\frac{pd}{gal}$

Now, the integration constant is:

$0.167 = 30 + C$

$C = -29.833$

The solution of the differential equation is:

$c(t) = 30 - 29.833\cdot e^{-\frac{t}{10} }$

Now, the quantity of salt at time t is:

$m_{salt} = V_{tank}\cdot c(t)$

$m_{salt} = (60)\cdot (30 - 29.833\cdot e^{-\frac{t}{10} })$

Where t is measured in minutes.

7 0

3 years ago

On a flight from New York to London, an airplane travels at a constant speed. An equation relating the distance traveled in mile

lions [1.4K]

Complete question :

On a flight New York to London an airplane travels at a constant speed. An equation relating the distance traveled in miles d to the number of hours flying t is t= 1/500d. How long will it take the airplane to travel 800 miles?

Answer:

1.6 hours

Step-by-step explanation:

Given the function :

Time t taken for flying distance d is given by:

t = 1/500 * d

Tine taken to fly 800 miles;

d = 800 miles

t = 1/500 * (800)

t = 800 / 500

t = 1.6

Hence, time t = 1.6 hours

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3 years ago