Answer: Less than.
Step-by-step explanation:
is less than 4 because
is 16. And
is 8.
Potatoes cost $1.20 / kg. If you buy 0.8 kg, how much are the potatoes? (Answer $0.96)
Answer:
Length 6, Width 2
Step-by-step explanation:
6x2 = 12 = Area
6+6+2+2= 16 = Perimeter
C would be the right answer
If
![A(t)](https://tex.z-dn.net/?f=A%28t%29)
is the amount of salt in the tank at time
![t](https://tex.z-dn.net/?f=t)
, then the rate at which this amount changes over time is given by the ODE
![A'(t)=\dfrac{3\text{ gal}}{1\text{ min}}\cdot\dfrac{5\text{ lb}}{1\text{ gal}}-\dfrac{3\text{ gal}}{1\text{ min}}\cdot\dfrac{A(t)\text{ lb}}{300+(3-3)t\text{ gal}}](https://tex.z-dn.net/?f=A%27%28t%29%3D%5Cdfrac%7B3%5Ctext%7B%20gal%7D%7D%7B1%5Ctext%7B%20min%7D%7D%5Ccdot%5Cdfrac%7B5%5Ctext%7B%20lb%7D%7D%7B1%5Ctext%7B%20gal%7D%7D-%5Cdfrac%7B3%5Ctext%7B%20gal%7D%7D%7B1%5Ctext%7B%20min%7D%7D%5Ccdot%5Cdfrac%7BA%28t%29%5Ctext%7B%20lb%7D%7D%7B300%2B%283-3%29t%5Ctext%7B%20gal%7D%7D)
![A'(t)+\dfrac1{100}A(t)=15](https://tex.z-dn.net/?f=A%27%28t%29%2B%5Cdfrac1%7B100%7DA%28t%29%3D15)
We're told that the tank initially starts with no salt in the water, so
![A(0)=0](https://tex.z-dn.net/?f=A%280%29%3D0)
.
Multiply both sides by an integrating factor,
![e^{t/100}](https://tex.z-dn.net/?f=e%5E%7Bt%2F100%7D)
:
![e^{t/100}A'(t)+\dfrac1{100}e^{t/100}A(t)=15e^{t/100}](https://tex.z-dn.net/?f=e%5E%7Bt%2F100%7DA%27%28t%29%2B%5Cdfrac1%7B100%7De%5E%7Bt%2F100%7DA%28t%29%3D15e%5E%7Bt%2F100%7D)
![\left(e^{t/100}A(t)\right)'=15e^{t/100}](https://tex.z-dn.net/?f=%5Cleft%28e%5E%7Bt%2F100%7DA%28t%29%5Cright%29%27%3D15e%5E%7Bt%2F100%7D)
![e^{t/100}A(t)=1500e^{t/100}+C](https://tex.z-dn.net/?f=e%5E%7Bt%2F100%7DA%28t%29%3D1500e%5E%7Bt%2F100%7D%2BC)
![A(t)=1500+Ce^{-t/100}](https://tex.z-dn.net/?f=A%28t%29%3D1500%2BCe%5E%7B-t%2F100%7D)
Since
![A(0)=0](https://tex.z-dn.net/?f=A%280%29%3D0)
, we have
![0=1500+C\implies C=-1500](https://tex.z-dn.net/?f=0%3D1500%2BC%5Cimplies%20C%3D-1500)
so that the amount of salt in the tank over time is given by
![A(t)=1500(1-e^{-t/100})](https://tex.z-dn.net/?f=A%28t%29%3D1500%281-e%5E%7B-t%2F100%7D%29)
After 10 minutes, the amount of salt in the tank is