In the table shown below:
Let N be the number of bottles filled,
Let T be the time in hours.
Given that the number of bottles filled is proportional to the amount of time the machine runs, we have
![\begin{gathered} N\propto T \\ \text{Introducing a proportionality constant, we have } \\ N\text{ = kT} \\ \Rightarrow k\text{ = }\frac{N}{T} \\ \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20N%5Cpropto%20T%20%5C%5C%20%5Ctext%7BIntroducing%20a%20proportionality%20constant%2C%20we%20have%20%7D%20%5C%5C%20N%5Ctext%7B%20%3D%20kT%7D%20%5C%5C%20%5CRightarrow%20k%5Ctext%7B%20%3D%20%7D%5Cfrac%7BN%7D%7BT%7D%20%5C%5C%20%20%5Cend%7Bgathered%7D)
Let's evaluate the value of k for each day.
Thus, on monday,
![\begin{gathered} N\text{ = 9900} \\ T\text{ = 5.5} \\ \text{thus,} \\ k\text{ = }\frac{9900}{5.5} \\ \Rightarrow k\text{ = 1800} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20N%5Ctext%7B%20%3D%209900%7D%20%5C%5C%20T%5Ctext%7B%20%3D%205.5%7D%20%5C%5C%20%5Ctext%7Bthus%2C%7D%20%5C%5C%20k%5Ctext%7B%20%3D%20%7D%5Cfrac%7B9900%7D%7B5.5%7D%20%5C%5C%20%5CRightarrow%20k%5Ctext%7B%20%3D%201800%7D%20%5Cend%7Bgathered%7D)
Tuesday:
![\begin{gathered} N\text{ = }11160 \\ T\text{ = }6.2 \\ \text{thus,} \\ k\text{ = }\frac{11160}{6.2} \\ \Rightarrow k\text{ = 1800} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20N%5Ctext%7B%20%3D%20%7D11160%20%5C%5C%20T%5Ctext%7B%20%3D%20%7D6.2%20%5C%5C%20%5Ctext%7Bthus%2C%7D%20%5C%5C%20k%5Ctext%7B%20%3D%20%7D%5Cfrac%7B11160%7D%7B6.2%7D%20%5C%5C%20%5CRightarrow%20k%5Ctext%7B%20%3D%201800%7D%20%5Cend%7Bgathered%7D)
Wednesday:
![\begin{gathered} N\text{ = }12330 \\ T\text{ = }6.25 \\ \text{thus,} \\ k\text{ = }\frac{12330}{6.25} \\ \Rightarrow k\text{ = 1972.8} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20N%5Ctext%7B%20%3D%20%7D12330%20%5C%5C%20T%5Ctext%7B%20%3D%20%7D6.25%20%5C%5C%20%5Ctext%7Bthus%2C%7D%20%5C%5C%20k%5Ctext%7B%20%3D%20%7D%5Cfrac%7B12330%7D%7B6.25%7D%20%5C%5C%20%5CRightarrow%20k%5Ctext%7B%20%3D%201972.8%7D%20%5Cend%7Bgathered%7D)
Thursday:
![\begin{gathered} N\text{ = }10440 \\ T\text{ = }5.80 \\ \text{thus,} \\ k\text{ = }\frac{10440}{5.8} \\ \Rightarrow k=1800 \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20N%5Ctext%7B%20%3D%20%7D10440%20%5C%5C%20T%5Ctext%7B%20%3D%20%7D5.80%20%5C%5C%20%5Ctext%7Bthus%2C%7D%20%5C%5C%20k%5Ctext%7B%20%3D%20%7D%5Cfrac%7B10440%7D%7B5.8%7D%20%5C%5C%20%5CRightarrow%20k%3D1800%20%5Cend%7Bgathered%7D)
It is observed that all exept wednesday have the same value of k.
Thus, the amount of time required for the number of bottles filled on wednesday is evaluated as
![\begin{gathered} N\text{ = }12330 \\ k\text{ = 1800} \\ T\text{ = ?} \\ \text{but} \\ k\text{ = }\frac{N}{T} \\ 1800\text{ = }\frac{12330}{T} \\ \Rightarrow T\text{ = }\frac{\text{12330}}{1800} \\ T\text{ = 6.85} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20N%5Ctext%7B%20%3D%20%7D12330%20%5C%5C%20k%5Ctext%7B%20%3D%201800%7D%20%5C%5C%20T%5Ctext%7B%20%3D%20%3F%7D%20%5C%5C%20%5Ctext%7Bbut%7D%20%5C%5C%20k%5Ctext%7B%20%3D%20%7D%5Cfrac%7BN%7D%7BT%7D%20%5C%5C%201800%5Ctext%7B%20%3D%20%7D%5Cfrac%7B12330%7D%7BT%7D%20%5C%5C%20%5CRightarrow%20T%5Ctext%7B%20%3D%20%7D%5Cfrac%7B%5Ctext%7B12330%7D%7D%7B1800%7D%20%5C%5C%20T%5Ctext%7B%20%3D%206.85%7D%20%5Cend%7Bgathered%7D)
Hence, the incorrect day is Wednesday. The amount of time for that many bottles should be 6.85 hours.
Answer:
x = 1.71
Step-by-step explanation:
![x^3-20=-15\\x^3=-15+20\\x^3=5\\\sqrt[3]{x^3} =\sqrt[3]{5} \\x=1.71](https://tex.z-dn.net/?f=x%5E3-20%3D-15%5C%5Cx%5E3%3D-15%2B20%5C%5Cx%5E3%3D5%5C%5C%5Csqrt%5B3%5D%7Bx%5E3%7D%20%3D%5Csqrt%5B3%5D%7B5%7D%20%5C%5Cx%3D1.71)
Question:
Find the gradient of the line passing through (6,8) and (4,10).
Answer:
-1 is the right answer.
Step-by-step explanation:
Slope of the line = The gradient of the line
Gradient of the line is known as change in the value of y-axis by change in the value of x-axis
Gradient = ∆y\∆x
![Gradient = \frac{y_ 2 - y_1}{x_2 - x_1} = \frac{(10 - 8)}{(4 - 6)} = \frac{(2)}{(- 2)} =\boxed{- 1}\\](https://tex.z-dn.net/?f=%20Gradient%20%3D%20%5Cfrac%7By_%202%20-%20y_1%7D%7Bx_2%20-%20x_1%7D%20%20%3D%20%20%5Cfrac%7B%2810%20-%208%29%7D%7B%284%20-%206%29%7D%20%20%3D%20%20%5Cfrac%7B%282%29%7D%7B%28-%202%29%7D%20%3D%5Cboxed%7B-%201%7D%5C%5C)
First, rewrite the equation so that <em>y</em> is a function of <em>x</em> :
![x^4 = y^6 \implies \left(x^4\right)^{1/6} = \left(y^6\right)^{1/6} \implies x^{4/6} = y^{6/6} \implies y = x^{2/3}](https://tex.z-dn.net/?f=x%5E4%20%3D%20y%5E6%20%5Cimplies%20%5Cleft%28x%5E4%5Cright%29%5E%7B1%2F6%7D%20%3D%20%5Cleft%28y%5E6%5Cright%29%5E%7B1%2F6%7D%20%5Cimplies%20x%5E%7B4%2F6%7D%20%3D%20y%5E%7B6%2F6%7D%20%5Cimplies%20y%20%3D%20x%5E%7B2%2F3%7D)
(If you were to plot the actual curve, you would have both
and
, but one curve is a reflection of the other, so the arc length for 1 ≤ <em>x</em> ≤ 8 would be the same on both curves. It doesn't matter which "half-curve" you choose to work with.)
The arc length is then given by the definite integral,
![\displaystyle \int_1^8 \sqrt{1 + \left(\frac{\mathrm dy}{\mathrm dx}\right)^2}\,\mathrm dx](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cint_1%5E8%20%5Csqrt%7B1%20%2B%20%5Cleft%28%5Cfrac%7B%5Cmathrm%20dy%7D%7B%5Cmathrm%20dx%7D%5Cright%29%5E2%7D%5C%2C%5Cmathrm%20dx)
We have
![y = x^{2/3} \implies \dfrac{\mathrm dy}{\mathrm dx} = \dfrac23x^{-1/3} \implies \left(\dfrac{\mathrm dy}{\mathrm dx}\right)^2 = \dfrac49x^{-2/3}](https://tex.z-dn.net/?f=y%20%3D%20x%5E%7B2%2F3%7D%20%5Cimplies%20%5Cdfrac%7B%5Cmathrm%20dy%7D%7B%5Cmathrm%20dx%7D%20%3D%20%5Cdfrac23x%5E%7B-1%2F3%7D%20%5Cimplies%20%5Cleft%28%5Cdfrac%7B%5Cmathrm%20dy%7D%7B%5Cmathrm%20dx%7D%5Cright%29%5E2%20%3D%20%5Cdfrac49x%5E%7B-2%2F3%7D)
Then in the integral,
![\displaystyle \int_1^8 \sqrt{1 + \frac49x^{-2/3}}\,\mathrm dx = \int_1^8 \sqrt{\frac49x^{-2/3}}\sqrt{\frac94x^{2/3}+1}\,\mathrm dx = \int_1^8 \frac23x^{-1/3} \sqrt{\frac94x^{2/3}+1}\,\mathrm dx](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cint_1%5E8%20%5Csqrt%7B1%20%2B%20%5Cfrac49x%5E%7B-2%2F3%7D%7D%5C%2C%5Cmathrm%20dx%20%3D%20%5Cint_1%5E8%20%5Csqrt%7B%5Cfrac49x%5E%7B-2%2F3%7D%7D%5Csqrt%7B%5Cfrac94x%5E%7B2%2F3%7D%2B1%7D%5C%2C%5Cmathrm%20dx%20%3D%20%5Cint_1%5E8%20%5Cfrac23x%5E%7B-1%2F3%7D%20%5Csqrt%7B%5Cfrac94x%5E%7B2%2F3%7D%2B1%7D%5C%2C%5Cmathrm%20dx)
Substitute
![u = \dfrac94x^{2/3}+1 \text{ and } \mathrm du = \dfrac{18}{12}x^{-1/3}\,\mathrm dx = \dfrac32x^{-1/3}\,\mathrm dx](https://tex.z-dn.net/?f=u%20%3D%20%5Cdfrac94x%5E%7B2%2F3%7D%2B1%20%5Ctext%7B%20and%20%7D%20%5Cmathrm%20du%20%3D%20%5Cdfrac%7B18%7D%7B12%7Dx%5E%7B-1%2F3%7D%5C%2C%5Cmathrm%20dx%20%3D%20%5Cdfrac32x%5E%7B-1%2F3%7D%5C%2C%5Cmathrm%20dx)
This transforms the integral to
![\displaystyle \frac49 \int_{13/4}^{10} \sqrt{u}\,\mathrm du](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cfrac49%20%5Cint_%7B13%2F4%7D%5E%7B10%7D%20%5Csqrt%7Bu%7D%5C%2C%5Cmathrm%20du)
and computing it is trivial:
![\displaystyle \frac49 \int_{13/4}^{10} u^{1/2} \,\mathrm du = \frac49\cdot\frac23 u^{3/2}\bigg|_{13/4}^{10} = \frac8{27} \left(10^{3/2} - \left(\frac{13}4\right)^{3/2}\right)](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cfrac49%20%5Cint_%7B13%2F4%7D%5E%7B10%7D%20u%5E%7B1%2F2%7D%20%5C%2C%5Cmathrm%20du%20%3D%20%5Cfrac49%5Ccdot%5Cfrac23%20u%5E%7B3%2F2%7D%5Cbigg%7C_%7B13%2F4%7D%5E%7B10%7D%20%3D%20%5Cfrac8%7B27%7D%20%5Cleft%2810%5E%7B3%2F2%7D%20-%20%5Cleft%28%5Cfrac%7B13%7D4%5Cright%29%5E%7B3%2F2%7D%5Cright%29)
We can simplify this further to
![\displaystyle \frac8{27} \left(10\sqrt{10} - \frac{13\sqrt{13}}8\right) = \boxed{\frac{80\sqrt{10}-13\sqrt{13}}{27}}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cfrac8%7B27%7D%20%5Cleft%2810%5Csqrt%7B10%7D%20-%20%5Cfrac%7B13%5Csqrt%7B13%7D%7D8%5Cright%29%20%3D%20%5Cboxed%7B%5Cfrac%7B80%5Csqrt%7B10%7D-13%5Csqrt%7B13%7D%7D%7B27%7D%7D)