Melody

This is how I would do it.

$$2-\frac{7}{9}$$

$$\\=1+1-\frac{7}{9}\\\\=1+\frac{9}{9}-\frac{7}{9}\\\\=1+\frac{2}{9}\\\\=1\frac{2}{9}$$

I'll repair my answer.

This time I will have 100cm in a metre instead of the 1000cm in a metre that I had before.

That might help  :))

They are pretty cool graphs Chris.     

See if this helps

Quick - where's the microscope????

Don't worry, I can't do it anyway.

Alan or LancelotLink might have better eyes. - Maybe  

Yes, well, you are smarter than Yogi.  That's for sure.  :)

(and he is smarter than the average bear)

Well Lancelotlink you have a whole team working with you.

Is that akin to cheating?

Maybe that is why chimp starts with ch ??     

The radius of the water surface is 1/3 the height of the water.

let the height be h and the radius be h/3     (in cm)

$$\\V=\frac{1}{3}\pi r^2 h\\\\
V=\frac{1}{3}\pi(\frac{h}{3})^2 h\\\\
V=\frac{\pi h^3}{27} \\\\
\frac{dV}{dh}=\frac{\pi h^2}{9}$$

$$\\When \;\;h=200\qquad radius=200/3\\\\
V=\frac{\pi\times 200^3}{27}=\frac{8\times 10^6 \pi}{27}\\\\
\frac{dV}{dh}=\frac{\pi h^2}{9}=\frac{\pi\times 200^2}{9}=\frac{4\times 10^4 \pi}{9}\\\\
\frac{dh}{dt}=20\\\\\\$$

$$\\\frac{dV}{dt}=\frac{dV}{dh}\times \frac{dh}{dt}\\\\
\frac{dV}{dt}=\frac{4\times 10^4 \pi}{9}\times 20\\\\
\frac{dV}{dt}=\frac{80\times 10^4 \pi}{9}\\\\\\
\frac{80\times 10^4 \pi}{9}=\frac{dV_{in}}{dt}-\frac{dV_{out}}{dt}\\\\
\frac{80\times 10^4 \pi}{9}=\frac{dV_{in}}{dt}-11000\\\\
\frac{dV_{in}}{dt}=\frac{80\times 10^4 \pi}{9}+11000\\\\
\frac{dV_{in}}{dt}=290,253\;\;cm^3/min\\\\$$

I think the water is being pumped into the tank at the rate of  290 litres per minute to the nearest litre. (edited)

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LancelotLink will probably have some great retort for my benefit  LOL

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Okay LancelotLink has has some fun at my expense.  He got Chimp Ayumu to do it.  She is one smart Chimp.

Our answers are still different.  Mine does look rather huge.    I'll have to look some more! 

How annoying.            

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It's all fixed now and I have a very good excuse!

Someone changed the metric system.  Who did that!

Now that there are only 100cm in a metre instead of my original 1000cm in a metre, it works perfectly.

DOH!

If you take away 90% of anything then there will only be 10% left

 10% of 2700

=10/100*2700

and you can finish it.

$$(3j^{-4}c^2)^3(-3j^{-6}c^{-6})^4\\\\
=(3)^3(j^{-4})^3(c^2)^3(-3)^4(j^{-6})^4(c^{-6})^4\\\\
=27j^{-12}c^6\times 81j^{-24}c^{-24}\\\\
=27\times 81 j^{-36}c^{-18}\\\\
=\dfrac{2187}{j^{36}c^{18}}$$