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**DJ Hobo** Attached is a sheet with a few problems that I either can't start, or can't finish.

In question 10, I'm having trouble with parts **c** and **d** (although, if/when I get the answer to **c**, I think I should be able to get **d**). It looks a bit blurry, but the number above the integrand sign is 4 and the number below is 0, in case there's any confusion there.

In question 11, I think my main problem is I don't know the steps, or the approach, I need to take. The only thing I've done so far for this particular question is find $\displaystyle \int_{0}^{4}{\left( 4x\; -\; x^{2} \right)}dx$ (and I don't even know if that particular step is relevant or helpful).

As for question 12; I don't even understand the information given. Could someone please explain it in more simple terms, please?

Any help here is, of course, greatly appreciated. (Nod)