Answer:
24
Step-by-step explanation:
If you go from 2 parts pineapple to 8, thats a 4x increase. Therefore 6x4=24 (6 from the Ginger)
You could get two different functions out of this:
<u>2x + 2y = 8</u>
1). <u> 'y' as a function of 'x'</u>
Subtract 2x from each side: 2y = -2x + 8
Divide each side by 2 : <em> y = -x + 4</em>
2). <u> 'x' as a function of 'y' :</u>
Subtract 2y from each side: 2x = -2y + 8
Divide each side by 2 : <em> x = -y + 4</em>
Those two functions look the same, but that's just because the original
equation given in the problem was so symmetrical. In general, they're
not the same function.
Answer:
The amount of oil was decreasing at 69300 barrels, yearly
Step-by-step explanation:
Given
![Initial =1\ million](https://tex.z-dn.net/?f=Initial%20%3D1%5C%20million)
![6\ years\ later = 500,000](https://tex.z-dn.net/?f=6%5C%20years%5C%20later%20%3D%20500%2C000)
Required
At what rate did oil decrease when 600000 barrels remain
To do this, we make use of the following notations
t = Time
A = Amount left in the well
So:
![\frac{dA}{dt} = kA](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%3D%20kA)
Where k represents the constant of proportionality
![\frac{dA}{dt} = kA](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%3D%20kA)
Multiply both sides by dt/A
![\frac{dA}{dt} * \frac{dt}{A} = kA * \frac{dt}{A}](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%2A%20%5Cfrac%7Bdt%7D%7BA%7D%20%3D%20kA%20%2A%20%5Cfrac%7Bdt%7D%7BA%7D)
![\frac{dA}{A} = k\ dt](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7BA%7D%20%20%3D%20k%5C%20dt)
Integrate both sides
![\int\ {\frac{dA}{A} = \int\ {k\ dt}](https://tex.z-dn.net/?f=%5Cint%5C%20%7B%5Cfrac%7BdA%7D%7BA%7D%20%20%3D%20%5Cint%5C%20%7Bk%5C%20dt%7D)
![ln\ A = kt + lnC](https://tex.z-dn.net/?f=ln%5C%20A%20%3D%20kt%20%2B%20lnC)
Make A, the subject
![A = Ce^{kt}](https://tex.z-dn.net/?f=A%20%3D%20Ce%5E%7Bkt%7D)
i.e. At initial
So, we have:
![A = Ce^{kt}](https://tex.z-dn.net/?f=A%20%3D%20Ce%5E%7Bkt%7D)
![1000000 = Ce^{k*0}](https://tex.z-dn.net/?f=1000000%20%3D%20Ce%5E%7Bk%2A0%7D)
![1000000 = Ce^{0}](https://tex.z-dn.net/?f=1000000%20%3D%20Ce%5E%7B0%7D)
![1000000 = C*1](https://tex.z-dn.net/?f=1000000%20%3D%20C%2A1)
![1000000 = C](https://tex.z-dn.net/?f=1000000%20%3D%20C)
![C =1000000](https://tex.z-dn.net/?f=C%20%3D1000000)
Substitute
in ![A = Ce^{kt}](https://tex.z-dn.net/?f=A%20%3D%20Ce%5E%7Bkt%7D)
![A = 1000000e^{kt}](https://tex.z-dn.net/?f=A%20%3D%201000000e%5E%7Bkt%7D)
To solve for k;
![6\ years\ later = 500,000](https://tex.z-dn.net/?f=6%5C%20years%5C%20later%20%3D%20500%2C000)
i.e.
![t = 6\ A = 500000](https://tex.z-dn.net/?f=t%20%3D%206%5C%20A%20%3D%20500000)
So:
![500000= 1000000e^{k*6}](https://tex.z-dn.net/?f=500000%3D%201000000e%5E%7Bk%2A6%7D)
Divide both sides by 1000000
![0.5= e^{k*6}](https://tex.z-dn.net/?f=0.5%3D%20e%5E%7Bk%2A6%7D)
Take natural logarithm (ln) of both sides
![ln(0.5) = ln(e^{k*6})](https://tex.z-dn.net/?f=ln%280.5%29%20%3D%20ln%28e%5E%7Bk%2A6%7D%29)
![ln(0.5) = k*6](https://tex.z-dn.net/?f=ln%280.5%29%20%3D%20k%2A6)
Solve for k
![k = \frac{ln(0.5)}{6}](https://tex.z-dn.net/?f=k%20%3D%20%5Cfrac%7Bln%280.5%29%7D%7B6%7D)
![k = \frac{-0.693}{6}](https://tex.z-dn.net/?f=k%20%3D%20%5Cfrac%7B-0.693%7D%7B6%7D)
![k = -0.1155](https://tex.z-dn.net/?f=k%20%3D%20-0.1155)
Recall that:
![\frac{dA}{dt} = kA](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%3D%20kA)
Where
= Rate
So, when
![A = 600000](https://tex.z-dn.net/?f=A%20%3D%20600000)
The rate is:
![\frac{dA}{dt} = -0.1155 * 600000](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%3D%20-0.1155%20%2A%20600000)
![\frac{dA}{dt} = -69300](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%3D%20-69300)
<em>Hence, the amount of oil was decreasing at 69300 barrels, yearly</em>
He would need a 93% on his fourth exam.
94+89+96+93= 372, 372 divided by 4= 93